2020 GMC Sierra AT4 6.2 True Dual Exhaust Overview

I looked for and listened to countless videos looking for the right exhaust. Exhaust note/tone and decibel level ( loudness ).
$800 for a bolt on cat back that may rust in a few years, or $1200+ for other brands that don't produce the correct sound.
This exhaust is customer from the cats to the over the axle section.
I'm still debating on removing the resonators...
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#GMCSIERRAAT4#truedualexhaust#coldstart

[@twomontess]

Well done ! I just order the borla s-type 2-1-2 exhaust for my 6.2 Denali.

[@GavDetails]

Nice!

[@alwaystruth4872]

I like it but I think it's a waste to get the complete upgrade. Should just swap the muffler with borla muffler. Doesn't make a big enough difference for the money it cost for the complete package.

[@twomontess]

Well Done

[@gk9417]

Great job 👍✌️🇨🇦

[@shockerracing]

Sounds good man!

[@GavDetails]

Thank you !

[@isaacrodriguez6582]

Sweet! What benefit does a true dual have? I have a 6.2 with a single flow master on it but have thought about going true dual jsut don’t know if it be worth it or if I’d notice a difference with anything

[@GavDetails]

The stock Y pipe is flat, which would restrict flow. I do not know if you would see a large HP difference. I was aiming for sound. There is a follow up video to this one where an X pipe is added. My previous truck was a 5.3 with the single muffler set up. I had one of these thrush mufflers on it. Videos of that are available as well. Good luck 🤙

[@tracygriffin6205]

Looks and sounds great. You are the first guy I've seen that swapped out the flattened portion of the left "Y" pipe. Nice job.

[@GavDetails]

Thank you for the kind words. Sounds better after the X pipe was installed. Check out that video if you haven't 👍👍

[@dustinparker6908]

@@GavDetails could u do a h pipe if you wanted to?

[@GavDetails]

@@dustinparker6908 I don't see why not. Instead of the X pipe, and H in its place.

[@dustinparker6908]

@@GavDetails okay cool

[@kevinarnott9484]

I think it’s so dumb that they run the pipe under the transmission pan , to where you can’t drop it , there should be a better way

[@phil955i]

Why did they pancake that section, I was thinking it was for ground clearance but looking at the new tube it's no lower than the front axle.

[@GavDetails]

Who knows, it was the same way on my 2016 Sierra with a 5.3L V8. Factory systems these days are brutal.

[@phil955i]

@@GavDetails I'm from the UK so not really up on your vehicles over there. I know that Jaguar pancaked the over axle pipes on the XK8 for clearance & that robbed power. Btw I'm researching the sounds of V8s running true duals as I love the old school muscle car sound they produce, I want to run true duals (without X or H pipe) on my '06 Mercedes CLS 500 for that reason. Everyone else runs an X-pipe on their CLS but it gives a raspier tone that I dislike.

[@GavDetails]

@@phil955i I have a couple more videos, there was a helicopter like flapping noise coming from the passenger tail pipe. An X pipe was added to alleviate this "noise." I too love classic muscle cars and the exhaust notes that they create. Kinney's muffler shop ( on youtube ) does alot of true dual setups. That is how I came up with the idea for my truck. They used one muffler on GM trucks where I opted for 2.

[@phil955i]

@@GavDetails OK cool I'll take a look at your other videos.

[@NXT_LVL]

It's for clearance and nothing else. They affectively want nothing to hang too far below the oil pan in trucks for "off road use" and last thing you want is something to get stuck to it plastic bag, Styrofoam cup etc. But in truth the place where it begins is at the head, the first inch after the flange... does it come out or dead head to the "log" style manifold or are the shorty style. Otherwise the design is strictly to keep the sound levels low for "sound pollution" California has a drive by sound level test. Tesla Model 3 failed it, tire and wind noise was now the only thing to make noise

[@davidbodnar1108]

What exhausted you use?

[@GavDetails]

The tubing/piping was purchased from summit racing and thrush welded (chambered ) mufflers.

[@frankierizzo5481]

Did you remove the flapper valve?

[@GavDetails]

Yes.

[@frankierizzo5481]

@@GavDetails Is there a particular reason you removed the flapper and not the resonators?

[@GavDetails]

@@frankierizzo5481 I left the resonators because I wasn't sure how loud it would be without them. They can always be removed at a later time. The flapper is welded to the single pipe section after the muffler so that entire section was eliminated. The flappers tend to vibrate and make a tin can like noise. There is no performance or MPG loss seen with it removed.

[@frankierizzo5481]

@@GavDetails Thanks for the reply!🤙

[@indianajets]

@@GavDetails that's actually not correct.. the 6.2 need some of that back pressure to help build torque. You are correct if you say no HP gain but there is some loss in torque by removing the valves.

[@kenmcfarlin7201]

Hi brother, I was wondering what muffler brand and model are you using on your truck it sounds awesome? Thanks

[@GavDetails]

Thrush welded mufflers. I believe 2.5" inlet and out ( for this set up both are offset ). There is an updated video with an X pipe added. Thank you for the kid words.

[@GavDetails]

Kind*

[@brianzaborowski2724]

Looks and sounds much better. If I had to criticize anything, most of the welding was a piss-poor job. Either his heart wasn't in it that day or was too lazy to grab his shield so he could actually see how crappy he was doing.

[@dedlock658]

i thought a Y pipe wasnt True Dual Exhaust thats i 1 into 2 and not a 2 into 2

[@GavDetails]

The factory exhaust goes like this, exhaust manifolds into a Y pipe, single in and single out muffler into another y pipe that separates the exhaust into a dual exit. The factory Y pipe at the front end was removed for 2 individual pipes that run into the X pipe ( later video than this ) into 2 separate mufflers.

[@dedlock658]

@@GavDetails ok so that isnt a True Dual as a TRUE dual would need to be a Single on each side that is a True Dual

[@GavDetails]

@@dedlock658 there may be some miscommunication here. There are 2 independent pipes on each side. What came from the factory was removed. Maybe the video does a poor job of showing it.

[@dedlock658]

@@GavDetails it says Y Pipe which is a 2 into 1.. not X pipe or independent

[@GavDetails]

@@dedlock658 In this video at the 1:15 mark, the flat section of the factory Y pipe can be seen. There is only 1 pipe the goes into the stock muffler. @ 4:55, I reference the " Y pipe " section that has been modified with a NON FLAT section. From 5:25-5:31 it is clear that there are 2 separate pipes. They individually go the length of the truck into their own muffler and single pipes exit the mufflers and continue to the rear section. This is the video where I got the idea from but they use 1 muffler: kzbin.info/www/bejne/f17SgWqJqdCXgM0 And here is an update video where an X pipe is added to my exhaust ( around the 7 minute mark ): kzbin.info/www/bejne/qX_WpYmEhcyCkLM

[@ReidHenderson]

I've noticed the factory does alot of dumb shit to factory exhaust. Like indented tubing and awful Y pipe setups. And all kinds of ugly things that make you wonder if the engineer had a mild stroke while designing it. You should see the factory horshoe pipe that comes on 2012 impala with the 3.6. Its a huge engineering Mona lisa!

[@bmbullard]

Does the new exhaust hang substantially lower than the factory?

[@GavDetails]

Negative. It is not any lower.

[@buckearly2009]

Damn,...that's some ugly ass welding. I worked for Kooks.

[@GavDetails]

Yes, the welds leave something to be desired. The party who did the work may have felt rushed. With that said, the bright side is that there are no leaks, no one can see it ( Truck is ceramic coated and almost always clean ) and living in the midwest, it will rust and be replaced in a few years. Thanks for checking out the video.

[@buckearly2009]

@@GavDetails my welds had to be perfect. They were inspected before shipment. I was the oldest and only white American on the welding line. Everybody else spoke Spanish. I knocked 30 hours off some jobs. Mustang GT. 60 hrs for 30 sets. Done in 30 hrs. My "Spanish" co-workers threatened to walk off. Guess who got fired??

[@gk9417]

@@buckearly2009 you sound bitter and racist 🇨🇦

[@jasonfranks2689]

Looks terrible

[@jaydoublebusy]

Resonators have to go...

[@GavDetails]

I have a couple more videos on the exhaust. I don't want it too loud. It sounds pretty good. They can always be removed in the future.

[@Maverick09171]

Dude, you need an x pipe or an h pipe. You shouldn’t treat the engine as two separate 4 cylinders. You’re not realizing all the gains you otherwise would be

[@GavDetails]

The truck was recently at a speed shop, they did not think an X pipe would benefit the truck. With that said, I have spoken to a shop about possibly removing the resonators. With that, it's possible an X pipe will be added. All depends on the amount of noise made.

[@Maverick09171]

Gav Details interesting. Not sure how that could be because an x pipe greatly improves scavenging. That “puttering” tractor sound your exhaust is making as some RPMs (in your other video) tells me you’d benefit from scavenging. Maybe seek a second opinion. Or better yet do before and after dyno runs. Prob gain 10-15rwhp

[@GavDetails]

@@Maverick09171 I have a tentative schedule to add an X. hoping for the next week or so depending on work schedule etc

[@Maverick09171]

Gav Details awesome! Keep us updated

[@phil955i]

Adding an X-pipe does help with exhaust scavenging but gives minimal performance gains. What it will do is give a more raspy tone. True duals gives the tone a more old school muscle car tone. An H-pipe is a good compromise between tone & power.