Tahoe 2024 GM Exhaust Upgrade

[Sean Michael]

Studying pictures online it appears the GM performance exhaust by Borla has a resonator before the muffler and no spring-loaded valve, while the GMPP Performance Exhaust (84888291) doesn't have the pre-muffler resonater but has the valve. I'm referring to the spring-loaded valve that's intended to help with DFM drone, we've established these trucks never got an active exhaust valve. This was just observed from looking at pictures, I've never set eyes on either in person.

I was leaning towards the GMPP version because GM actually qoutes an 11hp increase but they don't say the same for the GM by Borla version. Also, I'm assuming the RST Performance Edition uses the GMPP version from stock, and that truck is officially listed at 433hp, with GM stating most of that is via the exhaust upgrade. Makes sense, most people acknowledge that a CAI provides limited to no actual power bump, especially without a subsequent tune, and the RST Perf Edition only gets exhaust and CAI for its power bump as far as I know. I feel more confident the GMPP actually provides a bump in power, being that OEM car manufacturers tend to be conservative about officially listed power numbers. If that ~11hp bump is even noticeable in actual real world use is a whole other conversation.

I'm really torn, the GMPP is around $3,300 whereas a catback directly from Corsa or Borla is quite a bit less expensive. Also, the aftermarket cat backs don't have the valve, and I really want to avoid DFM drone, I read that it sounds like a helicopter when cruising and DFM activates. Guess I could play around with that mod people do to hold the stock valve open to see what it sounds like, that only costs a couple of hose clamps and a few minutes under the truck.

Someone help steer me right on this, I want catback exhaust, I would rather err on the side of a mild volume increase as opposed to being obnoxiously loud, and I absolutely want to avoid drone, which is a hard line for me - zero drone required. This truck is mainly driven by me, but I do take my family on road trips. I also would feel more justified spending the money for a HP gain, even if it's modest, and even if it's not necessarily percentable I would feel like it was more justifiable. If I just wanted more sound, I could have a muffler shop switch out the muffler alone for just a few hundred dollars compared to several thousand for a catback.

 

[iamlegion]

I think you are setting yourself up for massive disappointment if you think you’ll notice 11hp in a 400hp 5000+lb vehicle. That’s $300/hp for gains you couldn’t tell in a blind test and a gun to your head.

I can’t speak to the non GMPP systems but when I have a luggage rack and use any throttle on the highway you can hear it reverberate inside. If you have a family and tow or use the hitch you may not love it.

 

[ACHUN717]

Studying pictures online it appears the GM performance exhaust by Borla has a resonator before the muffler and no spring-loaded valve, while the GMPP Performance Exhaust (84888291) doesn't have the pre-muffler resonater but has the valve. I'm referring to the spring-loaded valve that's intended to help with DFM drone, we've established these trucks never got an active exhaust valve. This was just observed from looking at pictures, I've never set eyes on either in person.

I was leaning towards the GMPP version because GM actually qoutes an 11hp increase but they don't say the same for the GM by Borla version. Also, I'm assuming the RST Performance Edition uses the GMPP version from stock, and that truck is officially listed at 433hp, with GM stating most of that is via the exhaust upgrade. Makes sense, most people acknowledge that a CAI provides limited to no actual power bump, especially without a subsequent tune, and the RST Perf Edition only gets exhaust and CAI for its power bump as far as I know. I feel more confident the GMPP actually provides a bump in power, being that OEM car manufacturers tend to be conservative about officially listed power numbers. If that ~11hp bump is even noticeable in actual real world use is a whole other conversation.

I'm really torn, the GMPP is around $3,300 whereas a catback directly from Corsa or Borla is quite a bit less expensive. Also, the aftermarket cat backs don't have the valve, and I really want to avoid DFM drone, I read that it sounds like a helicopter when cruising and DFM activates. Guess I could play around with that mod people do to hold the stock valve open to see what it sounds like, that only costs a couple of hose clamps and a few minutes under the truck.

Someone help steer me right on this, I want catback exhaust, I would rather err on the side of a mild volume increase as opposed to being obnoxiously loud, and I absolutely want to avoid drone, which is a hard line for me - zero drone required. This truck is mainly driven by me, but I do take my family on road trips. I also would feel more justified spending the money for a HP gain, even if it's modest, and even if it's not necessarily percentable I would feel like it was more justifiable. If I just wanted more sound, I could have a muffler shop switch out the muffler alone for just a few hundred dollars compared to several thousand for a catback.

Hello. I’d advise just getting a borla muffler for $120 and have the muffler shop remove the stock valve. And then you can get a Carbyte which deactivates DFM and auto start/stop. My two cents. The muffler has no drone and is mildly loud. I know you don’t really want that option but I think it’s the best bet with family and all.

 

[Sean Michael]

I think you are setting yourself up for massive disappointment if you think you’ll notice 11hp in a 400hp 5000+lb vehicle. That’s $300/hp for gains you couldn’t tell in a blind test and a gun to your head.

I can’t speak to the non GMPP systems but when I have a luggage rack and use any throttle on the highway you can hear it reverberate inside. If you have a family and tow or use the hitch you may not love it.

Thanks for the info. So to clarify, you have the GMPP exhaust on your vehicle? Specifically the GMPP and not the GM by Borla exhaust?

In addition to the resonance you mention hearing with a luggage rack installed, what is your overall impression of the upgraded GM exhaust?

 

[iamlegion]

Thanks for the info. So to clarify, you have the GMPP exhaust on your vehicle? Specifically the GMPP and not the GM by Borla exhaust?

In addition to the resonance you mention hearing with a luggage rack installed, what is your overall impression of the upgraded GM exhaust?

Correct, GMPP.

I like it, it’s pretty tame but that’s what I wanted. I would say if you are a casual passenger and someone swapped the exhaust you might not even notice, maybe except under WOT. It’s definitely not obnoxious even under cold start-up. If you’re outside or behind the car it’s more noticeable but nothing that would bug your neighbors.

Materials are really good quality, install wasn’t bad except the cat donut flange was tricky to get lined up and sealed. I’m not sure the extra $ is totally worth the material quality and performance gains but cost wasn’t really a factor for me.

If you have money to burn and want something closer to an OEM sound level and you have reasonable expectations that 11hp in a body on frame SUV won’t be noticeable then I’d say go for it.

 

[Scarey]

Lots of stuff on exhaust, not sure where to start so I’m starting here. 2024 6.2 tahoe. Carbyte yes, gets rid of most Dfm. Next, muffler delete and valve? Is that too extreme or do I need to put some muffler on there? Just want something throatier but not obnoxious.

 

[ACHUN717]

Lots of stuff on exhaust, not sure where to start so I’m starting here. 2024 6.2 tahoe. Carbyte yes, gets rid of most Dfm. Next, muffler delete and valve? Is that too extreme or do I need to put some muffler on there? Just want something throatier but not obnoxious.

I’d say look for a good muffler. Muffler delete tends to drone and it borders on aggressively loud. I got a muffler and just installed some carbon fiber exhaust tips and had the muffler shop remove the valve.

 

[Scarey]

I might replace the stock muffler with a Flowmaster super 10. Keep everything else except the spring flapper valve. Question is, I was looking underneath and just ahead of the third cat converter there is a chunk of metal, 4”x6” 3/4 thick, welded to the side of the pipe. All by itself. Anybody know what this is, for?

 

[KMeloney]

From my Mustang days, I seem to recall that adding a freer-flowing exhaust without getting more air flowing into the motor would gain you some sound and maybe a couple HP, but would hurt torque. If that thinking is still true today, I'd recommend you go with a much-less-expensive muffler-only swap (unless you're going to add a blower sometime soon).

 

[Scarey]

I might replace the stock muffler with a Flowmaster super 10. Keep everything else except the spring flapper valve. Question is, I was looking underneath and just ahead of the third cat converter there is a chunk of metal, 4”x6” 3/4 thick, welded to the side of the pipe. All by itself. Anybody know what this is, for?

Does anybody know what that chunck of metal is, heat sink?