The Power of 2.5- vs. 3-Inch Exhaust - Engine Masters Ep. 9

You're sitting around with your typical street/strip V-8 and wondering, should I get 2.5-inch-diameter exhaust pipes and mufflers, or should I go 3-inch? In this episode of Engine Masters, presented by AMSOIL, we will help you decide, giving answers about power, tuning, and weight on 2.5- and 3-inch systems. You'll also find out about a very simple combo for 600-plus horsepower from a 454 Chevy! Finally, thank you to our new supporting sponsors, Mr. Gasket and Earl's Plumbing!
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[@DontTreadOnMeh]

You know what they should do is get a STOCK engine and try it, since most of us viewers don't have a 600+ hp engines in our cars, and most of us with trucks and muscle cars have small blocks, not big blocks.

[@claythompkins5087]

Even more so because the cam profile in a stock or mild engine will be effected much more by exhaust flow than a performance engine with little valve overlap and a sharp lobe profile.

[@fatalvenomX]

Clay Thompkins but even simpler than that a 600 hp engine puts out so much exhaust gas compared to stock that of course 2.5 is gonna be too restrictive compared to 3

[@dylanmorin2534]

life dont begin till 600+ hp haha

[@5.0_life30]

Amen to that brother!! I have an 04’ F-150 and would love to see how much HP these guys can squeeze out that bad boy. 5.4 Triton all the way

[@FernandoMartinez-mq2gj]

That_Ford _Guy don't blow a spark plug now lol

[@hueroski]

Good video. Would be nice to see numbers on a small block making say 300 hp to see if 2", 2.25" 2.5" and 3" would result.

[@focused313]

Agreed.

[@blackhatkid07]

+hueroski I would also love to see this comparison! Something a little more "real world."

[@InvincibleExtremes]

yeah, thinking a 2.5 inch would lose hardly anything on a 300 hp average smallblock... would definately be cool to see

[@elesjuan]

+hueroski Then run the test on those terrible buzzing pieces of trash the ricers put on their cars vs a real quality muffler. Not that ricers would care....

[@boingkster]

+hueroski A 2.5" exhaust on a 300-400hp smallblock is plenty. I have a good 2.5" mandrel bent system in my LS1 powered station wagon and love it - lots better than stock and a good note when you step on it but wont wake the neighbours when I go to work at 5:30am. I've heard the same car with a 3" setup from the same manufacturer and its obnoxious... might be necessary for over 400hp though.

[@Bolton115]

Well this has been interesting.. since my RV converted school bus really has over 20 feet of 2 1/2" exhaust, and its 500cid Cadillac V8 spends a lot of time making 550lbs/ft of torque below 2800 RPM.. it looks like the 2.5" setup is the right one for an RV situation where the engine is probably going to top out at 4800RPM-ish anyway. Sometimes, bigger exhaust isn't better.

[@nerradnosnhoj5122]

use that 2-1/2 " system with a x pipe and get the mufflers as far back as you can. If your engine is under 400 HP and you use an X pipe with 2-1/2" tubing, your loss would be less than same exhaust on a 620 HP engine for sure

[@tommurphy4307]

not impressed- all the fast caddies have chevy motors in them.

[@lobbyrobby]

I'd like to see this test on a 350hp small block and also test a restrictive factory muffler to a performance straight through muffler

[@henrymeynier5072]

Nust look at the point of 350 hp on this motor. Makes no difference.

[@jaybilis9723]

5 inch tip on a civic makes 600hp, ask any ricer.

[@72RR446]

LMAO

[@07slowbalt]

5 inch? They must be going small in your neighborhood.

[@sbrmilitia]

Does it have VTEC bro?

[@jaybilis9723]

@Stev Rex im not a republican, i dont live in Murica, im not white, im not a boxer, sooo, yea, fukwit.

[@kylebrett4673]

Ask any ricer, Any real ricers

[@SirSpinalColumn]

So thats where Harry went when he finished building racecars for Cole Trickle? Good to see hes still in the biz...

[@thatguy4087]

Well done sir.

[@motorhead1964]

Mine too....good example of having the right actor play the right part...Duvall im convinced can play anything set in front of him one of the greats...got alot of laughs from this movie ..

[@zombiebirdieking3041]

+David Ridout I want you to go out there and hit the pace car... Hit the pace car? HIT. THE. PACE. CAR.

[@SirSpinalColumn]

Watched Days of Thunder last night. Great film. Fuck Russs Wheeler.

[@roninblax]

+motorhead1964 Duvall could play Mandela and win an Oscar.

[@duygukayhanisaskank4915]

Old School "gear-heads" have known for decades that once you reach 600hp, a V8 engine demands 3" exhaust. The air-flow numbers demand it. Especially, on street-driven cars. On V8 engines below 600hp, a 2.5" exhaust is perfect...with free-flowing mufflers. A 3" exhaust system looks cool...but kills torque & HP throughout the power band. Respectfully, Ben

[@I_like_turtles_67]

3 inch to 2.5 tailpipes works great on mid 300 hp cars too.

[@duygukayhanisaskank4915]

@RAMBO JOHN J I strongly suggest you ditch the cats. Also, do some research. There are much better mufflers available. Borla Mufflers are OK. But there are better flowing mufflers on the market & they'll give you the "throaty" sound you're looking for; without sounding overly loud and like "gramps" old farm truck. Respectfully, Ben

[@2muchz]

Unless ur car is turbocharged then it's different

[@patrickhickman8723]

Thanks Ben, I am building a 6.0 with flat top pistons, 862 heads, a ss2 cam, and stock truck intake with slightly bigger injectors, I have 2.5 collectors off my variable headers, guessing about 425 is for a rock crawler. I was planning on just running 2.5 all the way out.......... you answered me up real nice.

[@duygukayhanisaskank4915]

@@patrickhickman8723 I sincerely appreciate your reply....sounds like an awesome build. I'm not being critical...but...why are you choosing to use a "stock truck intake"? In my...respectful...opinion, the characteristics of your "SS-2" cam profile and those 862 heads will demand more than that intake can deliver. My friendly advice is to speak to a Tech Adviser at the company who produced the camshaft. Most have a toll-free tech-line. When you call, have with you as much information about your build as possible. ie; camshaft info, flow numbers for your heads, piston info, etc. They'll ask several important questions & give you valuable information to help guide you to a more beneficial intake. About your exhaust system: Trust me, you won't be disappointed by staying with 2.5''. There are 2 logical enhancements to your chosen 2.5" exhaust: 1.) An X pipe...not too far downstream from the collectors. 2.) Opt for oval 2.5'' pipes...rather than the standard round. The X pipe will balance the turbulent exhaust pulses on both banks of your V-8 engine...GREATLY improving torque throughout the RPM range. An X pipe will also allow you to take better advantage of the useable horsepower produced...by placing that HP in a more effective RPM range. Oval exhaust pipes GREATLY enhance scavenging from the combustion chambers & provide a beneficial increase in exhaust velocity. Also, the oval shape allows more ground clearance. Regardless Patrick, I hope ALL works-out well for ya'. Best regards, Ben

[@gman68137]

I'd be interested to see how the manifold transition (3" to 2.5", vs 3" to 3" vs 2.5" to 2.5") affects power, and if the carb was tuned for the exhaust so not so rich.

[@Sky1]

I laid a 3" pipe after my morning cup of coffee this morning.

[@flyingdog1498]

You blew the Plumber?

[@jonathanbanta9456]

Sometimes we just settle for less....unless you are referencing your amazing girlfriend

[@Sky1]

Barely submerged as I drop the kids off at the beach

[@Fdeubcfhbbjhfd]

Ya ya did...one inch at a time. 🤣

[@tripifi9303]

Bruh you made my scrolling through comments waiting for the vid to load wayyyy less boring 🤣🤣🤣

[@8G00SE8]

Pulled a 6" drain pipe off my house and welded it on, can't hear anything any more but i'm sure I gained 13bhp or something.

[@Akashpagol]

lmao

[@captainsensible6939]

Brilliant! Your 6" drain pipe is only good if ice cream doesn't have bones in it.... See? I can sound like Magnaflow, yet I don't charge double the price others do! (Like Magnaflow! Wait! If you're here, you're already confused)

[@conorhogan2435]

Rok Gok nah bro, I did it and it was like 19 with a 3” pipe, you just gained like 50+

[@donellmuniz590]

Is that at the flywheel, or the tires?

[@joshstansberry9103]

Plus no worries about flooding

[@lilbmac7]

Wow! I needed to see this. I'm about to change out my exhaust for my 68 Buick.

[@stealthcon6975]

Love the slowmo cam of the dyno with the linkage movement and the spray of the fuel

[@catbutt4020]

Great, now do it with 300-400 HP... what most people have

[@bcepni00]

+little billy Host people have 300 hp cars! Where do you live?

[@raga1s]

+Barış Çepni he lives in USA maybe?

[@bcepni00]

raga1s Maybe he has a Camaro? I believe thise are like 300hp for the 3.6 litre v6 and 400hp for the 6.2 litre v8 model.

[@raga1s]

+Barış Çepni v6 11+camaro, mustang, charger, challenger, over 300 hp Plus v4 mustang and camaro has over 300hp too

[@bcepni00]

Is there a v4 mustang? Are you sure that Its not I4?

[@bvsandman]

Ahh, the back pressure nuts are gonna be in full effect.

[@lovethesmellofracefuelinth7374]

The stock exhaust on V8 Challengers have huge suitcase resonators and is unnecessary dead weight, so it was one of the first mods that we did on my SRT8 and went with 3" SLP loudmouths. They are one of the best choices because there's not much to them, and are super lightweight. They consist of open chamber racing bullets, and eliminates the reso's altogether. They sound absolutely amazing, and are the perfect match up with the gen3 hemis 💪🏼😎

[@CCCP1968]

Lol a mopar guy worried about weight? What a joke

[@marcuscoster6529]

Losing 20hp/30ft-lbs on a 620hp/580ft-lb car is a pretty small difference especially if you are not trying to improve drag times or something. If you want your car quiet, 2.5" full length with mufflers sounds like a pretty good option for a "modest" build if it works even on a big block pushing that much power.

[@cecilsabourin9462]

How about a test of a stock 350 from the early 90,s pickup ,headers ,y pipe (2.5 ) ,3 inch cat in +out , magnaflow 3 in +out ,3 inch side pipe exit ,single ,especialy at a modest 3500 rpm, u know , where most pickups operate maybe with an MSD package ? These dino tests wind up so fast to max throtle , ignoring cruising speeds, where u can actually smell the roses and check out the sites ,cruisen' Just sayin'

[@justmechanicthings]

the power change figures are not really the point of this video, more just debunking the "calculated back pressure = higher performance" myth

[@bobgraves5833]

@@justmechanicthings Just wanted to let you know that there is at least one other person out there that understands like you do. DF even said "these tests are done at WOT and not the way you would typically drive on the street". They joked about the myth several times which was another ample hint as to what the video was about. Keep on teaching on!

[@eliasfalser9963]

@@justmechanicthingsa pipe system can be caculated but not to make back pressure but to use the velocity and weight of the exhaust system to use it to "suck" in air while the overlap is occuring

[@krusher74]

they really should start talking as a percentage loss, its 3%! is that seat of the pants percevable.

[@julienfoss1392]

1:05 "620 hp 580+ ft/lbs of torque with a curve that looks like Scott Weilands cardiograph" HAHAHA

[@cerealfamine1]

haha omfg!

[@SirSpinalColumn]

+cerealfamine1 brutal

[@thunderduckie01]

+julien foss OMG, I'm ROLLING!!!!!!

[@gonzalotapia1250]

+julien foss Savage

[@Pocahonkers]

I'm not sure that's something to be really proud of. (The non-curve curve thing not the fact that the guy is dead, I didn't even know who the fuck this man was until he died)

[@badbimr]

Repeat this test with an H-Pipe or X-Pipe and also on an engine making 350-400 HP.

[@cybertree]

+Bill Panop With my first vehicle (96 Ford Bronco) I did this thing I called the *superpipe*, but it was really just *TWO pipes* going into *ONE pipe*, which then split into *TWO pipes* to the mufflers. And maybe it was just first car love or something, but it sounded badass, it was freakin perfect, moderate when daily driving, and loud when I wanted to be.

[@BlakesGarage]

That's a great idea! I have always wondered what the difference really is.

[@Th3unknownuser111]

Hopefully they see this comment. I'm interested in that as well.

[@OnDemandReefer]

I'd like to see this too. Is 3" a complete waste on a 350-400 hp small block.

[@brianhagan2619]

+Bill Panop Also repeat with a longer muffler

[@deltacharlieecho4732]

Really helpful video for my build. Thanks, I know this is an old video, but still a good one.

[@darylfitzgerald1327]

Really enjoyed this episode

[@bassinbob1965]

A heart attack took me out of the trade. I don't miss the industry but I sure do miss fixxin em. For 33 years I twisted pipe and had gotten really good at it. I also miss my 1970 Pontiac GT-37.

[@Antiganos]

Keep rockin on brother

[@charlesroer972]

know exactly what u r talking about .

[@bryanroupe8646]

That's a rare car

[@maxvolovich9407]

I found out that I had to have spinal cord surgery C5 and C6 fused together because of my balance and loss of feeling all over my body. I found that my hobby seeing that working with the justice department was not safe anymore. So I pulled the trigger and they told me I am not supposed to life anything heavy stand or sit for long times. I said what can I do! They said you will have to figure it out. So again I had gone back to my hobby fixing cars and renovating my house and planning to build my own shop and start my own business! Never give up always do what you love. Also a doctor can only give you a suggestion he is going to say what will keep him safe from malpractice. He will not say yes you can do your old job if it is heavy and dusty dirty. Just be smart about it. People like everything can brake down.

[@trillrifaxegrindor4411]

get some work done and keep on going

[@maximilianlindner]

This channel is so unbelievably awesome!

[@hgwaterous]

On my daily driver Chevy Caprice 9C1, this video helped me decide that the factory 2.5" exhaust is fine with muffler delete and long tube headers. A 20 hp loss on 620 hp is only 3%. Well worth it to be that quiet (on a daily driver). With a streetable cam, the L77 6.0 will still make over 400 RWHP.

[@kermitefrog64]

Love the Amsoil. I use it in all my equipment.

[@philballphotography]

So for folks who need a little math. The 3 inch system has a 7 square inch cross sectional area. The 2.5 inch system is 5 square inches. Thats a 30% difference in flow area. At the 600+ hp level it apparently needs the 7 square inches. If you have a 400hp small block you will therefore be just fine at 5 square inches (the area per hp ratio is the same as the 3 inch on the 600hp engine). Conclusion, 600hp engines need a 3 inch dual exhaust for best potential power 400hp engines need a 2.5 inch dual exhaust.

[@xXtReMeGrAfiXx]

Philip Ball was thinking same thing, this engine is no where near stock. Therefore more air wants to exit and 2.5 restricts this

[@indravatar]

If the engine only 150hp what size that optimal?

[@mustangecoboosthpp3869]

John Lingenfelter (RIP) and Borla would disagree with you. Lingenfelter built over 600 horse power Corvettes using Borla 2.5 inch exhaust systems.

[@philballphotography]

@@mustangecoboosthpp3869 I don't think you understood my statement. You can still make 600hp with. 2.5 inch system. But you'll be missing out on a few extra hp while you do it. Lots of times people stick with a smaller size to help get the pipes to fit under the car - especially with low slung corner carvers. Going bigger doesn't yield benefits but you are of course free to NOT optimize the system and miss out on some performance all you like.

[@Turnt_Reynolds]

That Scott Weiland joke hurt me on a spiritual level

[@frederickhorsman6292]

+Zackster698 That "joke" struck me as very callous. Stopped watching the video at that point.

[@AlphaMachina]

+nippaaa To live your life trapped inside of a mind that betrays you, your own mind, because of a sickness in the form of a mental disorder that is debilitating and completely devoid of any kind of relief. A pain and agony that you can't physically run from, because its part of you, is detrimental. Every day normal things that most people take for granted are so far out of reach. It takes away every part of you that makes you able to live your life like you feel you should, like you know you could if you could only feel better, even for a little while. So you find a way to run away anyway, escape the trauma and the pain that eats away at you every second of your life, a tiny moment within your misery where you can have some peace of mind. But your illness isnt gone, only momentarily pushed so far down that you can no longer hear it's constant nagging. But down there it grows meaner and harsher than ever and that momentary relief from that drug of choice is no longer your release but now a part of the beast of burden that you so desperately wanted to escape. Every time you pushed it down, ignored it, it got stronger and more hateful, more hurtful, and more resistant to your pleading for it to go away. Its not so easy. Not everyone is born into this world with a mind made able.

[@revolutionday1]

+Frederick Horsman Ditto, boss. We'll also be unsubscribing too, if it isn't addressed or dealg with.

[@zachb5508]

+revolutionday1 Did you post this somewhere?

[@arthurx333]

.

[@JimLBon]

Nice to see you confirming what I’ve always suspected.

[@70ragtop]

Would love to see this exact same test done with different types of crossovers on the 3" piping.

[@ronaldrey8474]

Didn't they do a H pipe and X pipe hp test but it's under subscription & not free on Y.T.

[@Faolan161]

I found with 2 cams, my 460 responded at low end with massive gains with an H pipe, but not so much with other cams...

[@302hobronco]

They should have tried an X pipe and H pipe in the test.

[@jbr496]

Was thinking the same thing. And throw in an EFI system that would compensate for changes in AFR on each config.

[@Antiganos]

They've done tests comparing exhaust patterns before, if not on KZbin it's probably been moved to MTOD thanks to Discovery.

[@angelgjr1999]

X pipe all the way bro. :)

[@karlhopkins713]

@@angelgjr1999 Depends on the car. On my 2v I have long tubes o/r x and spintech super pro streets. I had lm1, couldn't stand the rasp, so I gave it a muscle car sound, not some junky raspy car.

[@angelgjr1999]

Karl Hopkins Mine has staggered wheels (285) x pipe and cold air intake. What should I do next? Coils? I don’t want to lower suspension because roads are trash here and I need my spine intact. )

[@deplorableb.r.4211]

I use 5" galvanized steel dryer vent straight pipes.

[@andrewm.200]

lmfao

[@xaviercrowley7517]

While driving around town I saw a jetta TDI with a stock exhaust but he had an "aftermarket" exhaust as well....dryer hose right out from under his fender and up the side of the car...little plumes of black. Made my day

[@spedracer55]

lmao

[@DavidG-vq3bk]

Does the catalytic converter do a good job of catching the lint?

[@extremedrivr]

@@DavidG-vq3bk nah! Thats the cabin filters job. Hehe

[@jaxxx66]

Would be interesting to see a comparison using EFI and the same AFR

[@TheEZGZ]

Thanks again for this Multiview forever classic

[@ipoopedtoday4260]

I bet all ricers came here to take a look, what size fartcan will work better

[@shinviews4717]

W

[@josefs1234a]

+Andrius Čičirka its stupid, thats just the tip, u need the whole exhaust or open headers i hate honda idiots

[@ipoopedtoday4260]

jose sanchez I hate too. It's just a prank

[@ipoopedtoday4260]

W... Wait? Did you say that evey honda owner is idiot? Fuck you

[@minecraftlegand19]

+Andrius Čičirka 5 inch dumper ftw

[@95turbostang21]

Engine Master you should do an episode with the common size motor you would see people running in their cars like a 302 or 350

[@MormonMustang_]

LS vs Coyote vs 392

[@qq-hk2sq]

If they did a more practical test using an engine size most of us could relate to, the results would be less impressive and fewer mufflers that weren't needed in the first place would be sold. I don't consider a 454 a typical street/strip motor as they described it today.

[@Treeesmith]

Roger Carlin or a 250 I6

[@gt-37guy6]

It makes about a 2-3 percent difference. If you had 300 HP with 2.5" exhaust, you would gain about 5-10 HP...might be enough to feel...about like flipping the air cleaner lid on the old Q-jets, but don't expect some miraculous difference.

[@aamantium1]

@@qq-hk2sq I'm with you on this one. They seemed to be a more common street rod motor in the 90s

[@fstarockaburns425]

Love it - Starts with "mostly stock" - then its forged this, alu heads that, only thing stock is the casting # - possibly... :] Nice video thanks!

[@timvanderstarre9021]

Het said sort of stock bottom end that means only high compression pistons

[@davidstrouse4832]

I would like to see that same test on a more reasonable 450 hp small block engine.

[@RaimarLunardi]

the lower the less difference.

[@MediumHalf]

holy crap Freiburger, that Scott Weiland crack was darrrrk

[@claytonbyrd6134]

Lmao

[@numinous4789]

Exhaust pipe sizing has one ultimate goal if you're going for max power: exhaust gas velocity. Too small piping will choke the motor. Too large will lower the exhaust gas velocity and actually make less power. They key is to find the sweet spot for your setup. Bigger is most certainly not always better. A 4" single-exit exhaust on a high power Supra will not be good for a built N/A Civic.

[@JerseyMikeP]

+Numinous A chart to make choosing easier, courtesy of Dynomax;-) www.qsl.net/ya5t/techchart.jpg

[@numinous4789]

JerseyMikeP It's a little different for me, since I'm forced induction (2.3 DI Turbo running 25psi). 3" serves me great at my power level, ~380whp.

[@eviljgish9308]

Love this show I watch every episode

[@rondail5675]

Thanks for providing true results.

[@TheDicrio]

They missed the headline. For me, it's not a stretch that a 3 inch system made more power that 2.5 inch system, especially on a 454 cubic inch engine. The real news is a 2.5 INCH EXHAUST SYSTEM MADE 600 HORSEPOWER!!! Every "How to pick your exhaust system magazine article I have ever read, says 2.5 inch is only good to 425-450 horsepower, and the 3 inch system only picked up 13 horsepower? Wow, that doesn't justify the cost differential, fitment problems and additional weight to me.

[@06goatm6]

You guys HAVE GOT TO do a cat vs. no cat comparison. with proper tuning on each of course. I'm thinking like a LS3 with a tune with a stock catted exhaust vs. no cat exhaust (same mufflers), and a retune if necessary. Maybe throw in some high flow cats too.

[@lovethesmellofracefuelinth7374]

Have got 3" on my Challenger SRT8, and was one of the best mods that we did on it. Next to a good set of sticky drag radials, it's one of the best mods that you can do and recommend it for performance engines. SRTs come with pretty fat pipes from the factory, but have huge resonators/mufflers that I definitely recommend replacing and is the primary reason I did it. The 5.7 equipped cars come with 2 1/2, whereas the SRTs come with 2" 7/8s. The 3" definitely improve the sound, especially since I went with open chamber racing bullets and is basically almost like straight piping with improved flow. Is better though, because of the increased diameter

[@krusher74]

sound is complety objective.

[@Adventurebean541]

Can you guys do this on more of a stock motor. Like what most of us have. Mildly tuned engines with bolt on mods i.e. exhaust, CAI, programmer and other supporting mods without tearing into the engine. 2.5" vs 3" Great video and love what y'all have to say everytime! Keep up the great work!👍🏻Thanks guys!

[@rednecksworld2649]

Exhaust is always better when it's bigger. Your not looking for back pressure. Your looking for Exhaust scavenging. An x pipe on a 3 inch set up will always out perform an 2.5 set up or h pipe. But 2.5 inch pipe will give you gains with an x pipe. It's really all about making one exhoust pulse into a vacuum for the next pulse

[@jackdaniels2657]

@@rednecksworld2649 what about on a turbo motor? Would a 4 inch exhaust be better then a 3 inch exhaust on a stock turbocharged motor?

[@rednecksworld2649]

@@jackdaniels2657 that would be interesting. With a turbo, your not looking for exhoust scavenging. We already know a muffler on a turbo is restrictive. 3 inch exhoust is nice for exhoust flow but how big is to big. What problems will a 4 inch axhoust couse if any.

[@jackdaniels2657]

@@rednecksworld2649 like I said u need the restrictive backpressure cus without back pressure no spool and turbos work under load meaning backpressure

[@gordocarbo]

Big exhaust on a stock engine wont do anythingexcept make it louder

[@WDMetalman]

Ouch, Scott Weiland? Damn.. too soon brah. Lol

[@its_generik]

+yuck fou Brutal.

[@jason-ge5nr]

+yuck fou hes been drug free for like a year now.

[@urmomsayswhat3675]

+Albion Laster dude hes dead

[@its_generik]

urmomsayswhat dumbass

[@Pyrofries]

+urmomsayswhat that's the joke

[@wismar1971]

Id give up that HP and Torque to have a street car I can have a conversation in. Great show!

[@BigfootUnibrowMan]

@@davelowets Wouldn't a quieter, hence more restrictive muffler defeat the purpose of going 3" anyway? You only flow as much as your most restrictive piece can allow. Quieter mufflers usually have more baffles and restrict flow accordingly.

[@bradgriffith4231]

@@BigfootUnibrowMan The big 5x11 MagnaFlow muffs quiet things down pretty good without hurting power but bottom line is the more power it makes, the louder it is, unless it has some hair dryers on it to kill the pulse! LOL My 409 small block isn't bad with 2, 12" glass packs with good turndowns hangin on the end of the headers isn't terribly loud, until I hit the loud pedal!! Will finish the real exhaust one of these days with dual 2.5s running into a MagnaFlow with internal Y pipe & a single 3.5" out! Will still be loud but way quieter than now with zero loss of power.

[@MDAdams72668]

@@BigfootUnibrowMan they are mufflers that actually increase air flow BUT they are 800+ a peice

[@markmayfield2228]

Years ago I had an 85 Nissan King Cab 4X4. I put a 3 in with a Thrush turbo muffler on it. The muffler guy thought I was crazy. Loved it.

[@gmax341]

Wow spot on with the exhaust pipe shops! I called a place a few months ago that I had service done on a previous vehicle to try and get a quote on a simple muffler change. I wanted to replace my quiet Muffler with maybe a cherry bomb. Something to brighten up the exhaust tone a little bit on my E-150. That's all! All the piping and cats to be untouched, but they went on about how my engine needs back pressure and how it would have terrible tow power. I guess that shop loses my money and a customer because now I have to do the work myself.

[@blahber222]

my Civic has 4" so yeah I eat stangs fo dayzzzzzz. (this is a joke, please don't run over me Mustang drivers)

[@ArtVandelayOfficial]

+Roland Ocomen really funny punk!

[@Rotming]

+Roland Ocomen you never know with mustang driver lol

[@audiwankenobi361]

all last gen stock mustangs I beat no problem with my 4 cylinder.....I'm trying to figure out if a 3 inch exhaust would help make my domination be even easier.

[@sperlongatours]

+Motor Trend Channel *can you guys do an episode where u put a performance crankshaft on a European turbo v8 or v12 thanks*

[@PHILLY214]

+Roland Ocomen thats way to big..hahaha you need like a 2in full

[@XSniper16]

This show I think is equally as good as Roadkill and Hot Rod Garage.

[@Jameshair007]

for sure

[@tylerseitz6337]

You guys have inspired me to rebuild the 262 cubic inch V6 in my 1994 S10. I need one of you guys to lend a brain and a hand on doing it right though. I'm too stupid to do it on my own. But the truck is Roadkill worthy. It has 262,000 Miles on everything and has been parked outside every day since I bought it in 2016. You guys would like it. I'm sure of it. It's being done on a budget too. I'm sure you hear this alot, I am a diehard fan of your show. I love your work. It would bring me great joy to wrench on it with your crew. Then rub it in my dad's face for thinking that it's a dumb idea.🤣 That's my dream.

[@mrbillpurcell6203]

great compare ! thanks guys,

[@MakingCentsInTrucking]

You guys rock. Way to debunk an old myth. Awesome show!

[@brianoconnor8479]

see this is a good test but should do a more community oriented exhaust. if you should put a 3 inch tip or a 4 inch tip on your Honda and which makes more VTEC

[@knyghtkrawlr]

lmao. definitely the 4 inch

[@Lostlife656]

open header for sure lol

[@numberpirate]

+Brian O'Connor Imagine how much power that engine could make with DOHC and VTEC heads? 650hp @ 5200 rpms and/or 930hp @7500 rpms assuming relatively the same flat torque curve afforded by the bottom end, and the much higher rev range due to the different cam profiles. Def need 4 inch exhaust for anything above 5k though as evidenced by the tq dive at 5.1k. Is that because of the cams, valves, or carbs?

[@Nemesis_0311]

+Marcus Taber what the hell did I just read you just asked a theoretical question basically just said "imagine if honda v-tec engines had DOHC ".... they do but then you go on to assume doing this will put out silly numbers at random rpm points and then advise a 4 inch exhaust but then ask why it needs it? are you ok? unless you mean on the 454 in which case its make a bit more power v-tec isn't some magical thing it basically just makes a cam with low lift have increased lift when activated by lowering the cams. which it otherwise has high lift honda has v-tec for efficiency not power

[@axle.australian.patriot]

Great video. Glad you did most of it properly. Even though you part mentioned it you didn't provide the the tuned size (volume) of the exhaust matched to the engine. Being a 454 you probably are close to the correct volume with the 3 inch, but those pipes look way to long for resonance length. Here in Australia we mostly worked with 300ci engines so the 2.5 was a closer volumetric/sonic match. A 3.x inch worked well for tuned size and length for a single pipe system against the 300ci engines.

[@toddsizemore8376]

It would be interesting to see the a test with 3" to the muffler and 2.5" out the back...most cars are tight over the rearend for 3"...nice job guys...

[@greenteagod]

Scott Weiland's cardiograph, daaaaaaamn! Just for a straight swap though I don't get it. I mean if it's running that much richer on 2.5" wouldn't you want to retune?

[@stephenbrowne33]

yeah that was a bit fucked up

[@GladiusYTR]

agreed. they didn't check to see how much leaner you can run the carb before you start getting into overtemp/knock and how much power would come back. that would have been too scientific.

[@M3rVsT4H]

+John Klatt surely it's worth noting that the AFR never really went wildly outside of an ideal range.

[@greenteagod]

+M3rVsT4H kind of. I mean look at the flip side of this. if they had that tuned to the 2.5" and then switched to 3" and then just open headers with that little extension would it have not been running way lean? there were some spikes of leanness there. yes it's clear you are going to lose some power but it seemed that this was more of a 2.5" sucks video.

[@alexanderadams2538]

+John Klatt I think the comparison was that the carb was tuned for open pipes ie: max possible power output, and then they were going off of that tune to see how much power was lost by adding pipes.

[@krazyphucker369]

Had 2.25 dual full exhaust with a small block chevy went to 3 and it instantly went lean on fuel barely ran so I increased fuel and it definitely has better response and sounds great

[@billys4625]

I did 2.25" true dual exhaust with 8"glass packs on 2000 chevy silverado with 3" tips haven't noticed any power loss at all if anything it got more because I put 285/75/16 and it will smoke the tires like nothing when before I had 265/75/16 and they wouldn't smoke at all with stock pipes

[@mickjager5974]

Yeah I don't know how folks can stand a super loud exhaust. I had a honda 75- V twin shadow that previous owner had put straight pipes on. And like the one guys says after about 30 minutes of riding I had to get off it because I couldn't take the noise anymore! Vibration sucked too. They bike I had a couple before the shadow was a 700 V4 saber with stock pipes. Man that thing was so smooth and quiet! I loved that bike.

[@todd2902]

I could feel the difference in the seat of my pants a 2.5" vs a 3" way before dynos, no surprises here, good job! Running a 455!

[@devilsgarage7726]

that settles it, a 3 inch is going under my 1.3 ltr suzuki samurai.

[@mcard0627]

+devils garage yup.. because basically your 1.3 engine has to be at full, high revs all the time to do a proper speed.. ; )

[@jonathanbanta9456]

How could this be applied to a common Briggs and Stratton?

[@abram800932]

Jonathan Banta lmao

[@flyingdog1498]

I have twin 3"pipes on my 96 Geo Metro, what a difference that makes, 3 banger with an unbelievable 1000 ccs of raw power.

[@esoteric1213]

I like u

[@mattc8162]

Would like to see the results with high flow cats added to the 3" set up .

[@Ericlikestorun]

Had a super charged g37 on a dynojet dyno. had an off the shelf exhaust system. Customer had cut outs installed. Back to back runs with closed vs open cut outs. Closed made more power. No tuning changes in between.

[@markrod9145]

Great video! I have done the following in a couple of cars and wondering if it makes a difference if I go with a 2 1/2" system all the way thru. Ford 351C engine about 275 hp. At 3" header collector start with 3" pipe to a 3" muffler and then after the muffler continue with 2 1/2" pipes. I include an X-Pipe.

[@trillrifaxegrindor4411]

use common man parts and engines (under 400 horsepower 273's,289's,302's,283's,305's,318's,327's,340's,350's,351's,360's,400's etc) The last time i revved up to 6500 rpm was NEVER

[@realdeathpony]

Yep.. I see 2.5 for small blocks vs 2.25.

[@k.y.s_performace7038]

Probably because you obviously own a lemon of a motor lol. Our 383 shift at 7.800rpm lol

[@Sams88990]

​@@k.y.s_performace7038 That's his point. Most people rarely exceed the 4500 fpm piston speed threshold on stock, or one step up, parts. Do you turn your 383 at 7.800 rpm with a breaker bar, or by hand? I'd be fairly impressed with the latter....

[@thelikebutton4405]

K.Y.S_performace fr man I wanna see that. And to respond to the OP on this comment, my stock 345 hemi shifts at 6200.

[@k.y.s_performace7038]

@@thelikebutton4405 exactly, alot of people that run hemi's at the strip are spinning past 7000rpm with stock bottom ends. The original 426 hemi with a 727 torqueflight would shift at around 7250rpm and thats a bigblock lol

[@AdventureAwaits4u]

Might be splitting hairs but for this to be a true test would you need to tune after the exhaust was put on? The motor was tuned for open header then went rich with the 2.5" exhaust. Maybe lean it back out for some real numbers? You guys are awesome and I love the show just wanted to see what you thought. Thanks!

[@guardrailbiter]

Not splitting hairs at all. Your point is valid.

[@xmo552]

You know what guys.. I appreciate the objective tests, tips, and specs on your engine. Always. Thanks.

[@EmilEonoe]

Absolutely awesome video. Very informative. I'd like to know what the sound difference was between the two measured in decibels or whatever other metric. Thanks.

[@oistein74]

Brutal Weiland reference ;) But Great video. I think with a turbo car the difference would be even greater.

[@JerryWick]

Remember when Motortrend uploaded full episodes like this on KZbin?

[@bibble05]

I hope u have a brother named John

[@DrLoverLover]

No

[@bobgipson9330]

Growing up in rural central Indiana, I came across some pretty "colorful" auto enthusiast. I recall one 3rd generation inbreeder that found himself in quite an economic quandary regarding his dream exhaust system. One night all the local guys were in the high school parking lot with their cars, talking shop. We heard this drone that sounded like a really pissed off bumble bee. To our surprise the inbreeder in question pulled up with a "custom' 3 inch exhaust system comprised completely from the legs from a swing set. They were aqua blue complete with swirl pinstripes. They were bent under the rear axle and point more up than level Ahhh the memories of youth.

[@Ray00069]

My truck came with a stock 2.5in and I upgraded to a 3in and it made a whole difference of the world too.

[@davidwayneedwards2783]

How about a test of an engine making 350-400 HP with a 2-1/2 vs 3 inch exhaust?

[@mattevans1643]

It's virtually the same result.

[@trillrifaxegrindor4411]

WHAT why test something a normal,average ,everyday guy or girl might have in their car or truck? they need to test more top fuel and 700-800 horsepower unicorns none of us will ever own so we have useless data regarding parts we cant afford.

[@johnscudellari3314]

@@trillrifaxegrindor4411 if you test the lower hp cars the results would be minimal. The results already were minimal. 13 hp would not be seen on a track time. too many variables come in to play with that. My car is tuned properly for the 2.5 exhaust. I am willing to bet a 3 inch would make it a little louder, but minimal if any true gains.

[@extremedrivr]

@@johnscudellari3314 You really think 13 Horsepower is minimal?? Seriously?? 13 extra Horeapower is not minimal.

[@bvcxzgt5451]

When they have already proven a 614hp engine would only lose 2.8% of its power if you dropped to 2.5" and totally forgot to tune the engine for the new exhaust... I'm pretty sure you have your answer.

[@jimsmith5737]

Love to know what an old set of straight through Cherry Bombs would do.

[@cathygambill1554]

Y those mufflers are the same

[@romanduque2204]

Cherry Bombs? might well use Tuna Cans.

[@brianhoefer7148]

About to add 3" turbo back to my 3.5L twin turbo F150. Turbo provides back pressure as well as muffling.

[@Steven-hj6nl]

Not every muffler guy is the same. Also you have to keep in mind the car that can except a 3" system. Another thing is the sound. Not everybody wants it so load that the car becomes not enjoyable to drive for long periods of time. I own Custom Exhaust in Hanover Massachusetts and have been bending pipe for almost 40 years. Yesterday redid a 55 Chevy because he swapped out the 427 to a 6.2 LS. This car is slammed to the ground with all sorts of mods done to restrict ease of even bending 2 1/2" pipe. I am a guy who loves Magnaflow due to the straight through flow and low interior drone. Great choice in the pick of mufflers. Any time I see you on the TV I watch because your funny and cool gearhead. I also have to say that you have a twin. I have a customer that looks like you. Did a mint 83 Chevy wagon 3" Magnaflow system on and asked him if he was you. His daughter even said that you and him look alike and do the same kind of stuff. Keep up the good work and if you are ever in my area, feel free to check out my place. I have a wall of 200+ pictures of my work. I am sure we would have a lot to talk about. I am going to do a 70 Pontiac Lemans with a seriously built 455. 3" with Magnaflows, I generally make the over the axle pipes but flow and no the expense thing is open, got 2x 3" mandrel bent 90 degree pipe. I don't have a mandrel bender so do I what can. Should be fun.

[@redkingrd]

11:02 me explaining to my crush why im the better choice

[@Jesusprayerwarriorbw]

Yeah boy

[@matthewjenkins1161]

Right, so a gap of just 13bhp, about 2% of total power between 2.5" and 3", which could be partially closed by optimising the fuelling. For any application where noise level suppression is desirable, I'd think the 2.5" would be the way to go.

[@vaugr1917]

Dual 2.75 with tuning for the win

[@hightechredneck_0566]

Been dying to know this. Thank you for doing this test.

[@eduardbruno1920]

Good work,good advice.

[@jjmac3561]

It would be even more interesting to see different throttle positions used to give a better idea of general driving use instead if just flat out.

[@ashtonmariefranklin725]

If they would've put an x pipe in the system it would balanced left anx right banks, and should've improved tq numbers.

[@tommykelley3948]

That exhaust set up on the motor look like it’s long enough to go on a SHIP‼️

[@weffyj6427]

Interesting test. For 620 hp 3" exhaust is the obvious choice, and I'd also have a cross-over pipe between the banks to equalize the system (which for some reason you did not test). However, it might be another story for a real-world street engine that needs to make vacuum and not just peak HP.

[@jackdaniels2657]

Cross over pipes add back pressure

[@ericmcginnis9413]

That would make for a good episode! Comparing turn downs verse lets say a 3 inch exhaust, or side pipes! Considering the weight difference, the shorter the better!

[@kellismith4329]

Stacks

[@garyburgess3829]

Glad to know this about the 3 inch exhaust..that's what's going on mine..

[@simplycorvettesc3corvettes659]

Surprising results. I think the best compromise For A Street Car would be 2.5 inch and exhaust cut-outs just ahead of the trans crossmember. The reasons being beneath 3500 rpm you loose torque (but no hp) with 3 inch exhaust. SOME backpressure will contribute to Where the Torque is "felt", meaning seat of the pants. That's what I'm doing with mine. Block huggers for no ground clearance issues with speed bumps & driveways, electric exhaust cut outs just ahead of the cross member to manage Where this combination will make the torque & this acts like an extension of the collecter using 2.5 inch pipes throughout and I like Dynoflow mufflers so I'll go with them. I don't feel like 3 inch is warranted with cutouts because it IS a street car after all so low rpm drivability as well as mileage are considerations and where will it spend the majority of its rpms? The cutouts won't kill the power, it's be just like running an open exhaust with a long collecter length. Besides, how many street cars are really making 600hp? Stick to an "overbuilt" engine that "only" makes 425 or so hp & put it on the bottle for the rest. N2O. The durability will allow it to safely operate up to 600+ hp, the nitrous makes that happen & the lower hp makes your engine last longer. Plus mileage.

[@Mackze]

But how much power do you lose cause you're running richer with the 2.5" exhaust? Only then would it be a fair comparison if you ran the same AFR...

[@OMGnanerpus]

+Jalmarification I was thinking that too. Really should have re-tuned it after putting the 2.5 on and then gotten some better results

[@VcArena]

i mean, geez, that much power, its kinda common sense that you would wanna run 3-inch. how about trying this on your typical 350hp-450hp small block which most of us budget people will have. hell put it on a 5.3l and show these guys what happens when they change exhaust.

[@5hift6ear]

3 inch is the way to go if you want more power. Coming from the Honda scene this was the case every time even on a 1.6L engine.

[@junechris]

I had an air gap intake and demon carb on my .40 over camed Camaro years ago, was a nice set up.

[@wildestcowboy2668]

Camaro is GM and it's garbage boy, should of had a man's car with a Big Block Dodge under the hood.

[@ltwig476]

Put 3" on my 390 FE with headers and glass packs. It really woke up. But the noise pollution is really hard to get used to. I wish there was some sort of slight baffle I could use on the end, instead of a more restrictive muffler just to make it not sound like open headers.

[@EchoOfGecko]

I'm curious how much of a difference re-tuning the carb for the 2.5" exhaust would have made.

[@fckuyo3918]

This is the real question.

[@AB-80X]

If it was set up properly for the open headers, which is probably the case as Brule is one of the best carb tuning guys in the industry, it's not that hard to calculate. You have to remember the fact that while you can tune it for better AFR, it does not change the fact that the system as a whole moves less volume. The amount the AFR goes down, is basically the same as the amount of air flow lost. In this case, you would not see much by tuning the carb - maybe 5-6 hp at best.

[@hoghogwild]

+ABOisen69X Agreed, if the carb was set up for the longtubes with the 18" collector extensions, recalibrating the engine would be beneficial when adding any sort of full exhaust. Gains/losses from tuneup between swapping between the 2-1/2" and 3" would be minimal.

[@patrickhickman8723]

the longer the exhaust is, the more restriction it has........ maybe this needs to be explained in this video as well, drag on the walls etc. some engineering calcs need to be run.

[@tommurphy4307]

@@AB-80X at what rpm? WOT?

[@chrisjamesbehan]

Would love to see a turbo application test. Turbos inherently are an exhaust blockage to start with; would be interesting to see the lost horses and tqs between a 2.5 and 3”er 🤔

[@tommurphy4307]

LIKE THE ONE GUY SAID- try with a stock motor

[@kensmechanicalaffair]

That's the real test.

[@liamteetz1329]

I used a hose to direct all exhaust gases back in the intake. Free Boost pressure, no turbo, no supercharger. Havent been able to start it yet, must be due to the tune, but once I get that done, you are looking at least 135% more bhp.

[@willheines4]

Well I can tell you a muffler delete on a 2004 Yukon XL sounds great. Now I need to figure out a good cam for it (lm7) and get it tuned.

[@raychingcar7881]

Regardless of the diameter you’re using, your flow is limited to the smallest area within the exhaust. You could have a 10” pipe, but if any where between the start of the flow and the end, you have an area that narrows down to 1”, then 1” is all the flow you’ll actually get. This is why a complete mandrel bent system is the preferred way to go. I have found that when running duals, equalization of pressure between the two sides generally helps with the torque. Having a cross over not only sounds better, it can help make more usable power.

[@faaaaq]

thats not entirely incorrect but you are missing MANY details. Say you take a 10 foot pipe, 3 inches in diameter. Replace a 1 inch length of it with 2 inch diameter pipe (with a smooth transition between the pipes, such as using reducers). that is FAAAAAR less restrictive than if you did the same but replaced a 2 foot section instead. Quick real-life test to prove how dramatic the length of the narrowing can affect restriction: go grab a straw, and cut it into two straws, one of them like 1/2 inch long. take the longer one and breath in thru it as hard as you can. Now do the same with the super short one. you will notice FAR less restriction on the short length of straw. Like way way less. Same applies to exhaust. Got a small pinch in some headers to make them fit an engine swap? likely wont even cause a measurable difference in power or airflow. have a header pipe that the entire length of is as small as the diameter of that pinch point? definitely will notice. Also, whether a "cross over" sounds better or not is a matter of opinion. I much prefer true-dual when it comes to sound, and when it comes to power on most vehicles it will not make a noticeable difference. And interesting test would be to see how having an X or H pipe affects different diameter pipe differs. I would assume on 2.25inch pipe, it would have a more noticeable impact than on 3 inch pipe, since if the motor has plenty of (literal) breathing room, any "equalization of pressure" between banks wouldnt have an impact on how the engine breaths. X/H pipes arent magical power-adders and "equalization of pressure" between banks also doesnt ensure ANY benefits. Like everything, it has a time and a place.

[@lelandlewis7207]

What would the 2.5" do with the carb tuned for it? How did the fuel curve compare with the 3"? Would be interesting to show the affect of fuel ratio on power and why you need to tune the carb for any changes.

[@ThatE30Guy]

Precisely. Whenever any changes are made to an engine's volumetric efficiency, the fuel and ignition really need to be re-optimized for those changes to make it fully worthwhile. This applies to anything from carb+dizzy to fully electronic fuel+ignition. I would also like to see how the power on this test engine looks with the 2.5" exhaust and a re-tune of, at least, the fueling.

[@bff1316]

I had 2.5 OD pipes on my little 468 CID, OEM was 454. I thought somebody had stolen my engine and dropped a small block in there. I looked and it was still my engine. Place two 3 inch pipes all the way back. Sounded like a deep low rumble, idle 425 RPM. Stepped on it and it sounded like cut outs and the 580HP showed through. This was in my Cherokee with replaced drivetrain. A bit of a sleeper.

[@alfredbrown7693]

Would like to see more variables. 2.75 in system. Remember restrictions under the car. How about 2.5 to muffler and 3.0 after? 2.75 to muffler and 3.0 after? This was great info thanks.

[@yurishnirman3847]

watched it back than, now that I am actually doing something for my truck, I realized that up to about 420HP basically no difference. and since my truck does not make that much power to begin with, I think I be ok with 2.5" dual.