C8 Corvette Kooks Header And Cat Test Shows Very Confusing Results!

Kooks asked us to redo our C8 Header tests in a specific manner to see if their header lost power, also to see if the combo (header and cat) gained vs either piece individually. I'll be honest, there were some very surprising results. The nut shell seems to be the setup works best together.
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[@divinedriftofficial]

Kooks needs to change their name to crooks lol

[@terryfong2906]

Thanks for your extensive testing and hard work. Guess I am putting my header money toward new wheels.

[@ruberube2855]

Lmr did a test with American racing header there high flow cats and exhaust and pick up 34hp

[@Miccio1]

Note to self: Don't waste your F###ing time and money on headers. Yeah, good idea, spend 2 grand for 10 HP.

[@nyplantingsgardendesigners5645]

It is a tough call for sure. The factory is bringing up horsepower and efficiency every year and surpassing the aftermarket with innovation like direct injection and dual fuel systems like on the ZR1. Yet we are expected to keep bolting on the same set of pipes that shops have been using for decades. On the other hand, if headers can reduce cylinder pressures in my supercharged Z06 and make the combination safer will be excellent. I cannot get straight answer from any of the high profile shops.

[@borderwave2]

Agreed. GM has probably spent over a million dollars developing these OEM headers. The engineering resources of an aftermarket header are much smaller in comparison.

[@KJC2025]

Won’t these numbers double when tuning becomes available?

[@triedproven9908]

Kooks tried to pull a venturi effect getting more exhaust velocity through smaller piping.. doesn't work in these modern engines. They need the volume of large diameter. Whoever makes a true 3inch full exhaust 1st wins.

[@skip741x3]

I wouldnt be suprised....why a company , creating these would not at least Match OEM port sizes and tubing,collector diameters is beyond me...the 3" would likely open the top end breathing and move the torque peak alittle higher in the rev range

[@mikekosar6135]

Air flow would have to come at an angle

[@stevesmith6236]

Hell of a lot of work and substantial cost for a mere 10-11 hp gain. Doubt that will show with a time slip. Not worth it.

[@mogulme6190]

I guarantee it’ll show on a time slip... and it’ll probably pick up more once the car can be tuned

[@thereissomecoolstuff]

Dang, you were one of the first to try the LTH's. Everyone seems to be having the same results. Crazy.

[@richardtisdale3245]

American Racing just came out with their's and it has a true 3 inch collector

[@donalddooley209]

Thanks Andrew and Eric for these testing

[@jd4810]

A very informative video. I'm glad I watched it before committing to buying headers. I researched further and others had similar findings though their testing and investigation was not as thorough as yours. Excellent work.

[@Sean_Farmer]

Thanks for doing this test which consumed a lot of time for you guys. You really did it in a very scientific manner which some other people fail to do at times. I do think it sounds good and maybe when you're able to tune the car you'll see gains that are more in line with what we would expect, especially with a decent intake to match.

[@craigleidigjr4170]

Thank you. That was a lot of work. To show us and Kooks

[@kdom0710]

awesome awesome data video... well worth the watch

[@spyderlyf3]

It's the wing..too much drag on the dyno🧐

[@jonathantullos561]

Thank you for doing all the checks you really help me make better decisions on the upgrades for my car I live in Texas if not I would have you do all my work.

[@camillecarter1784]

Always learning from your videos. Not going to change anything, but it's good to know.

[@dannyh5700]

Still can't wait to see what ARH comes up with.

[@FrenchUsaEUC]

I was thinking to do that mode for my C8, but for the cost and headache for only 10hp, nope.... great video!!

[@EGGINFOOLS]

You could probably get more hp from the stock setup with flowmasters 😆.

[@king-o-vetts9899]

Way too many people in this business would either fudge the numbers a bit or editorialize in order to make them seem better than the data shows in order to keep the manufacturer happy. Thanks for telling it like it is. I don’t think 10 hp is all that disappointing considering that you are already starting with stock header and not a manifold. Also, don’t forget that the mitigating factor could be the stock mufflers. Everyone has to make their own assessment as to whether they are worth it. Keep it honest and keep it coming.

[@SRfastZ]

Good testing Andrew 👌

[@dlasti]

Interesting. Good testing.

[@dirtysouthtv2209]

Andrew, If the Kooks header pipe/connector was slimmer, the first connection would have to kind of match that-then they could enlargen the pipe or connections from there.

[@curvs4me]

AFE Power headers are supposed to add 17hp/24ft-lbs

[@DailyElectrician]

do the headers and cats work with factory valved exhaust? thanks!

[@23nedlog]

Extensive work and testing. Excellent effort and worth the time for all of us interested. Thanks Andrew and everyone at CSP!

[@spencersecord3073]

Awesome test! I can’t believe how low the oil pressure is

[@frazztrainman2187]

You did all that testing id be happy to just have the car i ordered a year ago !

[@franksoto7698]

Me too!!!😆

[@boydie1940]

Thanks for all the 😓 CSP! I love it no”FAKE NEWS”

[@414Chevy]

You guys have a lot of patience. Nice back to back test. Thinking Kooks wanted you to do five pull run because the C8 does what other GM cars have done. When you do back to back pulls, it must go into a "race" mode, car senses you are racing, so fuel/timing reflect that. Went to Kooks site last night, that's $2,800 and change for 10 HP. Yeah, no thanks, unless you're bracket racing for a 5k pay day on a regular.

[@maddog9659]

Real men of genius..

[@bigd9848]

Hard work 😓 putting on taking off🥵I guess the end result will be the best ✊

[@RobertKohut]

Nice!!

[@fh5tuningredlinemotorsport766]

When tuning is available I would like to see what they make with a catalytic converter delete

[@petercarey6883]

It would be interesting to see you do a cat delete using the factory headers. You should include a decibel meter in your tests as well.

[@joemeyers1016]

Do you think you could of made more power with the Kooks if you could tune the ECU? On past GM vehicles tuning for headers shows the biggest gains especially on the torque based ECU stuff.

[@completestreetperformance]

No, the timing and fuel is exactly where I would have put it. I see no reason it would gain. At least not substantially. Good question though.

[@MeanGreen3m]

Can you port the outlets and inlets, or is the entire length smaller? Not that you should have to.

[@arzemagic]

I’m sure I read somewhere that Kawasaki on the racing bikes used Narrow headers than the road going version because the gas moves faster through a thinner tube. Obviously this has to be optimised for the race engine. I’m also guessing that with the difference in the stock headers and the kooks cat would cause a lot of turbulence?

[@ranmas2004]

Hmm....so what results if you just straight pipe the stock exhaust manifold??

[@wydopnthrtl]

Probably the best all around value for only a bolt on.

[@rba4847]

seen a air filter for the c8 give 10 whp

[@7470alexander]

Now all you need is complete Corsa exhaust for the rest.

[@EGGINFOOLS]

So save your money.. Nice work showing us.

[@raulgutierrez6415]

A catless comparison would be worth a try, Also a custom stock header with 3” pipe from where all the tubes meet.

[@ST-bk5uf]

Other channels are finding good results with. a) stock headers, Soul cat,Soul exhaust and b) LTH headers, cat bypass factory exhaust. They found 20 hp using those setups.

[@kdom0710]

ofcourse, if they're adding the exhaust... This video did not take into account the Exhaust, im sure if they did, they would have gotten atleast 20hp as well.. what i've determined is that Every Vender makes the same power... its just a Matter of Which company you want to support

[@PhillyDee215]

Cool 😎

[@arzemagic]

Did you have the stock cats in place When you first tested the kooks headers when turned out you lost hp with the headers?

[@completestreetperformance]

Yes, twice we ran that test

[@christopherbegil1904]

You Should try the american racing headers . Love the channel I like that you dont suger coat stuff

[@anthonycosta1776]

Did you look into American racing headers. They seem to be the best I have seen.

[@MALR7]

What is the reason behind the power increase on the 3rd run?? Seems weird and counterintuitive as the car gets hotter , do you think they rely on cat-overtemp to come in and add fuel ?

[@jkfonyi]

It’s n/a heat soak isn’t huge issue and as oil gets hot it thins and stuff loosens up a bit to give small bump in hp .

[@garymathews4042]

what oil brand works best with this car set up ?

[@juliofernandez6310]

What gear are your dyno pulls in?

[@myxrutefalcon269]

I think you will find the kooks are a bit smaller because it is not a boosted car and with such a short exhaust system it needs a little BACK pressure. Don't forget on a na motor bigger isn't always better.

[@lawyers9]

I bought a set of headers with hi flow cats off of EBay for $700.00. Had them installed and picked up over 40 HP. Bought and installed a set of chambered mufflers for less than $300.00 and picked up another 10 HP. I would have to say the Kooks are not worth it. I don’t know what they cost, but would expect they are very expensive just for the name. Good of you to take the time, money and effort to do the testing. They should reimburse you!

[@jameswalton8927]

Hello will you be at Carlisle next week?

[@completestreetperformance]

Thinking about it

[@Pepsvette]

...thank you for all of the work that you guys put in...Emelia's aftermarket work ruined hers..I'm afraid that Tadge Juechter is somewhere laughing his @$$ off..will order a convertible Z06 in 22...

[@brandonnixon7105]

Test LTHs products next

[@anthonycosta1776]

Hey Andrew I been hearing these c8s are a bitch to work on and much more labor in comparison to the c7s. What do you think.?

[@raythemanroe]

Soul 🐈 with factory headers

[@alwayshungry24]

Emelia Hartford sent me here.liked subscribed and rang the bell

[@rus19297]

Does Kooks make a Green cat for the C8 yet? Wonder what it would do.

[@completestreetperformance]

They only offer the Green cat, actually it's the step up called the ultra green, basically a bigger diameter so more flow.

[@dgvette1]

Have you tested other headers?

[@c8racer621]

Hard to hear. Need a wireless mic. Thanks for sharing this info

[@jerredx7998]

Expensive 10 hp

[@Trading-Freedom11]

I guess the stock are very good compare to older cars. My ss picked up 50rwhp with lts and no cats and intake . 10rwhp for that much money might as well keep saving to get a cam kit ,then get the lts etc..

[@dgvette1]

Stock air box?

[@Alex-pl1ye]

New mod ported cats 😂

[@4BillC]

Smaller pipe = high velocity = better scavenging. That'd be my thought on it. Doesn't always work that way way but this time it did I guess.

[@dennisrobinson8008]

On 350-400 CI Engines spinning to approx 8000 RPM the 1 3/4" to 1 7/8" primary size long tubes seem to be doing best.

[@alexvillalobos7137]

Idk man smc have always used 1.75-2.00 inche headers. Anything different is probably because of the tuff figment in the rear engine corvette

[@robertbarnes2419]

Have you checked out emelia Hartford’s you tube channel and her c8 vette yet?

[@inv8999]

Use a catless pipes if they have..I don't know it's legal in US or no

[@revrocks3]

Port out the Kooks cats to match the factory headers and I'll bet you have a winner! Or.....get a different brand.

[@Venom99street]

GReAt WoRk - NOW GET A WIRELESS MIC for your videos please ! sounds like whispers.

[@1982DrH]

+1

[@bdd1469]

Dang. Been a fan of kooks for a long time but it looks like they have jumped the shark. Sad times we live in.

[@scottschneider5866]

Lmr was picking up 30 hp and 44 ft lbs of torque with American racing headers and there hi flow cats, the arh headers are 2.87 inches at the outlet noticeably bigger than the kooks, I would pass on the kooks , lot of time and money, they need to re engineer, also keep up the good work with the charity 👍🏼

[@ssoffshore5111]

The aftermarket cats probably have a lower cell density (freer flowing) than the stock cats making the matrix less restrictive. The smaller pipe diameter at the collector and cat inlet on the Kooks will possibly make more tq on the stock engine, but will likely choke the engine with future mods (heads, cam, etc). Going to the stock headers with the smaller ID inlet Kook cats likely lost power due to the smaller diameter opening of the cats, that big lip should create a big bottleneck.

[@skip741x3]

its crazy that aftermarket headers and cats are choking down the flow and using Smaller diameters! like Seriously? who does that? the collector and pipe tubing may also be smaller..dont know if that was ever measured

[@Vetteman372]

i hope kooks is paying you thats a lot of work

[@tejasfelix5577]

🤔🤔🤔🙄🙄🙄 Magna flow high flow cat's next week?? That would be sweet.. 🤔🤔🤔

[@zioo3117]

Why doesn't Kooks relieve the openings in its headers which are smaller than the stock openings? Af

[@backwoods5oh]

You should look into stainless works im sure they have to be better than kooks. But I may be a little biased since they're on my stang

[@completestreetperformance]

They do not have a c8 header at the moment

[@backwoods5oh]

@@completestreetperformance that sucks their high flow cats are really good.

[@completestreetperformance]

The kooks ones are honestly better. I think the inlet is too small though.

[@backwoods5oh]

@@completestreetperformance yes the inlet is small. Idk I've seen to many cat issues with kooks to want to buy. And the stainless works ones helped my car put down almost 500 n/a on the dyno so I'm probably just being biased 🤷‍♂️

[@7470alexander]

Corsa exhaust for the rest.

[@bertg.6056]

So much sound, fury and money for 10HP?

[@cedriclarouziere9301]

10whp for stainless header + cat is not so good. Chevrolet did a good exhaust.

[@douglasfeil2422]

No PA plate yet??

[@douglasfeil2422]

nevermind.

[@wydopnthrtl]

When GM designs their exhaust they use CFD (computational fluid dynamics aka "CAE") and tons of time validating for all driving conditions. It's not until you start to move significantly more air will you see any real value in just bolt on exhaust. Add a booster and then the cost vs power increase will become more reasonable. So far... I favor the ARH's

[@ahmedal-mawlani5284]

Well that just showed if you wanted your c8 to be louder just buy an axle back system lol

[@mrh3085]

Get a set of American Racing Headers or Stainless Works.

[@MarkJCarruthers]

Yes the mis match.

[@pro5.019]

Save your money you could have put in a K&N filter and gained 10 hp.

[@Vetteman372]

On the KOOKs header set up is not worth the money it cost for 7 hp 2000.00-2700.00 for 7hp no way

[@htownsfinest87]

Thats crazy, happy i didnt go with them.

[@joels6736]

2.2% hp gain doesn't seem worth the 4k price tag for headers and cats. I think just less money would be better spent on ultra performance tires and some track brake pads. Someone will eventually come up with a better header/cat system but the stock headers look pretty good and the stock cats while the medium might not have the best flow, do have good volume. As time goes on and the aftermarket learns and grows it will be interesting to see what full bolt-on mods will do.

[@toddbowers5673]

3 inch but tapers to 2.5 and 2.75 but tapers to 2.5?

[@mikekosar6135]

Lol 😂 Let me mess up my perfectly good corvette..🤪 I mean fiero

[@campingforayearrenoheart5908]

It sounds better that’s all that matters v8 America 🇺🇸

[@dirtysouthtv2209]

Stupit 😂🤣😂 Get em Andrew!

[@caseywinningham3000]

Emeila sent me here.....

[@completestreetperformance]

Tell her thanks! Lol

[@JayDancer-ds9gk]

When tuning comes available those headers and cats are going to fall flat on their face cause of those small flanges.

[@dirtysouthtv2209]

2 and 5/8’s...lol

[@rodtaylor62]

Victor racing spoiler check it out

[@dansherwood9851]

has it shut up you know this is a skewed test. Headers are part of the puzzle that go with other parts and a good tune. Once you do those I think you'll see a 20 to 30 horse at the wheels with those headers.

[@paulh373]

Your temp tag expired