Muffler change only.

[Teegunn]

I'm looking for a little more low end growl for my new 2023 AT4X 6.2. Nothing dramatic. The stock sound is so quiet, I can't even hear the engine, inside or out. Don't want to shell out 2K for a complete catback system from GM. Have looked through all threads here about muffler swaps, most are about the factory Borla catback system. Straight piping/muffler delete is too loud, plus will have drone. Don't want drone.

Going through many Youtube videos, it seems a Flowmaster or Magnaflow are the most likely options. I would try just a Borla Touring muffler, but can't find just a Borla Touring Muffler, every link when I google is for the full Borla catback system

I am leaning towards Magnaflow. I realize it initially isn't much louder than stock, but still has more low growl/rumble. I just want a little low rumble and bit more aggressive sound, but not obnoxious. And supposedly after a few thousand miles or a few months the Magnaflow breaks in for a bit more volume, but still no drone. The flowmasters - which I know are now made in China - have more growl and punch, but also sounds like they do have some drone at hwy speeds. I was thinking Flowmaster 40, flowmaster 50 or flowmaster FX. All 3 sound good, but again concerned about hwy drone, so leaning towards the Magnaflow as everything I read and have watched on YT says no hwy drone with the Magnaflow.

Any input or suggestions would be welcome! Anyone who has done just a muffler swap taking out the stock muffler for an aftermarket please chime in with your experience. Hwy drone level is my main concern. Also wondering if I do this, if I should have them cut out the flapper valve or leave it in. I plan on keeping the resonators at this point, researching it seems deleting or covering up the resonators has a negative effect on fuel mileage.

Thanks!

 

AT4 Forum Fav 👍

KBH Center Console Lid Armrest Cover for GMC Sierra - Grab one through Amazon!

[Cc1999]

I am doing pretty much what your asking about tomorrow.
‘I will post some start up sound videos. I shot the stock warm startup video tight. Tomorrow morning I record a stock cold start video. Then follow those up post new Corsa pro series muffler videos of the same criteria.

 

[Teegunn]

I am doing pretty much what your asking about tomorrow.
‘I will post some start up sound videos. I shot the stock warm startup video tight. Tomorrow morning I record a stock cold start video. Then follow those up post new Corsa pro series muffler videos of the same criteria.

Great! Can't wait to here how it sounds!

 

[Cc1999]

I know I put these in my truck thread, but thought I should probably share them here as well.

Stock cold start

Corsa muffler warm start and revs.

Installed pics of Corsa Muffler.

 

[Bwalsh00]

I swapped in a Borla Atak muffler and deleted both flapper valves. Left the resonators and stock tips on. It’s a loud cold start but the sounds mellows right out.

 

[Bwalsh00]

I swapped in a Borla Atak muffler and deleted both flapper valves. Left the resonators and stock tips on. It’s a loud cold start but the sounds mellows right out.

Borla 400844 Sbc Hot 350 383 https://a.co/d/aOyfa0H

 

[Cc1999]

I swapped in a Borla Atak muffler and deleted both flapper valves. Left the resonators and stock tips on. It’s a loud cold start but the sounds mellows right out.

Where is the other flapper valve?
I Deleted the one right in front of the muffler. I didn’t know there was another one under there.

 

[Teegunn]

Where is the other flapper valve?
I Deleted the one right in front of the muffler. I didn’t know there was another one under there.

Interested in the answer, also. I only see one flapper valve, which I have clamped to the open position currently. If there is another, I may try clamping that open also.

 

[Bwalsh00]

My 2020 w/6.2L had flapper valves immediately before and after the muffler. I kept the muffler in case anyone ever wants to put it back on. It’s currently up in the garage loft. I’ll try to find a pic.

 

[Cc1999]

I shot a cold start video of the AT4X with Corsa muffler .

 

[usmcfiredog]

I shot a cold start video of the AT4X with Corsa muffler .

Now I wish I went this route instead of a full cat back

 

[Teegunn]

Now I wish I went this route instead of a full cat back

Yeah, sounds as good, or better, than a full cat back Borla system.

I personally don't see the need to spend 2K+ for the full cat back system.

 

[usmcfiredog]

Yeah, sounds as good, or better, than a full cat back Borla system.

I personally don't see the need to spend 2K+ for the full cat back system.

I feel you on that but when I saw that it didn't void my warranty when the dealer installed it. So I paid 2k total for the exhaust and installation. Its not that I am not happy with it but I feel bad when I wake up my kids when I leave for work lol

 

[Teegunn]

I feel you on that but when I saw that it didn't void my warranty when the dealer installed it. So I paid 2k total for the exhaust and installation. Its not that I am not happy with it but I feel bad when I wake up my kids when I leave for work lol

I get the warranty concerns. I've already got concerns since I went with the RC 1.5" front level and RC 3.5" UCA's. It really depends on the dealership and how they want to handle warranty stuff. Obviously I would never expect or try to get the dealership to warranty the changes made to the front suspension, but there is the possibility they could try to wipe out most if not all of the factory warranty upon seeing I have the front level/UCA's AND bigger new tires (34x11.5) and -13 offset 18x9 aftermarket wheels.

I will have a free oil change coming up at any GM dealership (first oil change is free with these trucks - pretty common). I am not sure I want to even chance them seeing the front level and tire/wheel changes and then noting it in their system, flagging my truck to be voided on warranty.

I am not too concerned about just a muffler swap, I think the only thing they could say with that is that obviously the new muffler isn't going to be covered. But again, you never know, they might use ANY change from stock to void a bunch of stuff.

It's a valid concern, for sure. And for the first time ever I bought an extended warranty - 5 years 100K miles - on bumper to bumper on the whole truck. It cost me 3 grand to do that, and the main reason I did was the emissions system error problems on my 2020 AT4 3.0 diesel that they never could get figured out or fixed and also would not cover under factory warranty, which I feel was BS.

I can, at any time, get a pro-rated refund on the extended warranty I bought. So at this point I'd probably get about $2900 back in a check if I change my mind on that extended warranty. I have always scoffed at these extended warranties offerend when buying a new truck, but this time was different given my issues I dealt with. Thing is, there is NO guaranteed even the extended warranty would not possibly be voided, or partially voided, given the (rather minor) changes I have made to the truck. Insurance companies always look for a way out of paying out...

 

[roy826ex]

Service manager where I bought my truck said anything past the cats will not void a warranty unless it’s proven the changes caused the warranty issue to begin with which a muffler swap won’t mess anything up he said. He also told me they’re not one of those dealers who wants to mess with a customers about add ons and warranty related stuff anyway. Some dealers are petty about that kind of thing though and it does happen.