2025 2500HD ZR2 6.6L gas exhaust mod

[JoHURT]

need the opinion of someone sabby with the 2500HD 6.6L gas engine…
Traded in my 2022 5.3L Tahoe RST, had a true dual split Y-pipe, with an H-pipe into a dual inlet dual outlet Magnaflow and dumped before the axle.. ran phenomenal!! MPG’s and power band over all was spot on…
Thinking of doing the same to this new beast of mine, but it’s my first time owning a 6.6L and with the Alisson trans, my exhaust tech took one look underneath and saw what looks like a 3rd cat (no sensor attached) just after the Y-pipe, he began to tell me this speal about back pressure and if I split it as described previously as on my Tahoe I might lose rather than gain…
Okay fellas let the thread begin ….
I should also mention that my Tahoe had an AFE CAI, and a JET Performance MAF.. and the plan is to add those same upgrades to my ZR2 2500

and to make it clear, this is my daily driver and the suggested upgrades are solely to gain a bit more power to tug 37”s , overall better performance & MPG’s….

 

[KLA]

Good question. Waiting to hear people's opinions.

 

[AXE]

I would buy a complete system that is designed for the truck from one of the big companies that put in the testing and can show you any gains on a dyno. Gains are not likely to be noticeable on a big ol 8000+ lbs truck. But a dyno would show something even if it's 8-15 hp.

20% of at Hottexhaust.com

@SGRACING is probably the best guy to address this, as he builds performance motors and race rigs.

Hottexhaust

Shop catalytic converters & performance exhaust parts. Fast shipping, fitment help, and trusted brands for cars, trucks & SUVs.

www.hottexhaust.com

 

[JoHURT]

I would buy a complete system that is designed for the truck from one of the big companies that put in the testing and can show you any gains on a dyno. Gains are not likely to be noticeable on a big ol 8000+ lbs truck. But a dyno would show something even if it's 8-15 hp.

20% of at Hottexhaust.com

@SGRACING is probably the best guy to address this, as he builds performance motors and race rigs.

Hottexhaust

Shop catalytic converters & performance exhaust parts. Fast shipping, fitment help, and trusted brands for cars, trucks & SUVs.

www.hottexhaust.com

What’s your take @SIGRACING regarding my forum topic ?

 

[Roach769]

Also super interested in @SGRACING's take on this.

 

[bmcmay]

Good morning,
By chance any progress on this? I just purchased ZR2 2500 traded in my AT4HD 2500 I had put a MBRP stainless steel cat back system sounded great, just need to do the same to the ZR2. I checked with MBRP, BORLA, MAGNUM flow...nothing because of the suspension/shocks are in the way I was told. They have to create a need angle.

 

[AXE]

Good morning,
By chance any progress on this? I just purchased ZR2 2500 traded in my AT4HD 2500 I had put a MBRP stainless steel cat back system sounded great, just need to do the same to the ZR2. I checked with MBRP, BORLA, MAGNUM flow...nothing because of the suspension/shocks are in the way I was told. They have to create a need angle.

Any exhaust shop can do the necessary piping. There's plenty of videos on YouTube of 2500HD gassers with new exhausts.

 

[JoHURT]

Any exhaust shop can do the necessary piping. There's plenty of bodies in YouTube of 2500HD gassers with new exhausts.

Yeah, so I ended up cutting out the 3rd cat and replacing with the same 3 1/2” pipe, removed the factory muffler and went with a Borla 3 1/2” truck 24” muffler, I cut the tailpipe and dumped it right after the rear axle. I also installed MSD’s blaster coils, Moroso Ultra 40 8.5mm wires and a set of AFE stainless steel headers…. No lie, 35-40% gain in MPG’s and not too loud which is what I wanted. I don’t like loud “Takuache” annoying exhaust. Truck runs beautifully, I wasn’t looking at increasing horsepower cause my intention is to not race this 8000lb tank but to gain its full power potential

 

[JoHURT]

Yeah, so I ended up cutting out the 3rd cat and replacing with the same 3 1/2” pipe, removed the factory muffler and went with a Borla 3 1/2” truck 24” muffler, I cut the tailpipe and dumped it right after the rear axle. I also installed MSD’s blaster coils, Moroso Ultra 40 8.5mm wires and a set of AFE stainless steel headers…. No lie, 35-40% gain in MPG’s and not too loud which is what I wanted. I don’t like loud “Takuache” annoying exhaust. Truck runs beautifully, I wasn’t looking at increasing horsepower cause my intention is to not race this 8000lb tank but to gain its full power potential

Forgot to mention I also installed an AFE cold air intake and swapped my mass airflow sensor with a JET Performance MAF

 

[bmcmay]

Forgot to mention I also installed an AFE cold air intake and swapped my mass airflow sensor with a JET Performance MAF

Thank you for responding. You put a lot of work! Thank you again.

 

[D2500]

What did that all run you? If you don't mind asking. My old 2500 HD gas. I added magna flow exhaust I loved it. I want to do the same but I'm sure gas vs diesel is never going to be the same.

 

[scubatech]

The Borla system cost me $1800.00 from GM performance. My dealer said if I bought it through them they would install it for $100.00. So I did. I liked it. I'm not sure if I gained any power but it sounded good. I called Borla and they assured me it would not drone. That was my main concern. It was quiet on the highway. That was in 2023.

 

[8ball_99]

FYI, flowmaster has a dual exhaust for 6.6 gas now. Won't work with the 5th hitch package though. I put a Borla S type cat back on mine. Was around 1250 at summit racing. Super easy to install, just bolts on.

 

[Byrds8]

FYI, flowmaster has a dual exhaust for 6.6 gas now. Won't work with the 5th hitch package though. I put a Borla S type cat back on mine. Was around 1250 at summit racing. Super easy to install, just bolts on.View attachment 26158View attachment 26159

The Borla S-Type is what is on mine as well. Sounds pretty good. Dont think it is as loud as the dual was on the 6.2L though. I wanted to just get the Black Widow muffler but no one around here can bend 3.5" pipe.

 

[8ball_99]

The Borla S-Type is what is on mine as well. Sounds pretty good. Dont think it is as loud as the dual was on the 6.2L though. I wanted to just get the Black Widow muffler but no one around here can bend 3.5" pipe.

It's about right for me. I can hear it start up from across a parking lot or while im still inside a building. Cranking up in my garage in the morning it's pretty loud inside the house, lol. Driving it's not as loud, but I actually think alot of that is the side exit on the passenger's side vs duals out the back on the 1500. With the windows down on that side, you hear it pretty good. I had a Magnaflow and it was louder and a little deeper. But it droned constantly at highway speed. Got old pretty quick on long trips, especially towing. I really like how the Borla is only loud when you're getting on it and quiet while cruising.

 

[Byrds8]

Maybe one day down the road I’ll get LTHs lol

 

[D2500]

FYI, flowmaster has a dual exhaust for 6.6 gas now. Won't work with the 5th hitch package though. I put a Borla S type cat back on mine. Was around 1250 at summit racing. Super easy to install, just bolts on.View attachment 26158View attachment 26159

I added Magnaflow on my old 2019 HD 2500 gas. Is sounded awesome.
I do miss the sound now I have the 2500zr2 6.6 diesel. Love the truck but miss the rumble.

 

[double d]

Has your 2500 ZR2 gasser with Borla exhaust set off any codes, causing the check engine light to turn on? After I installed the Borla on mine, it happened twice. Code P0031 Ho2S heater control circuit low bank 1 sensor 1. Any suggestions? If I take it to the dealer, will it be covered? I cleared the code but it returned about 2500 miles later.

 

[Byrds8]

I have the Borla S type on mine and have never had an issue. It’s a TB but that shouldn’t matter.

 

[MO_ZR2]

Has your 2500 ZR2 gasser with Borla exhaust set off any codes, causing the check engine light to turn on? After I installed the Borla on mine, it happened twice. Code P0031 Ho2S heater control circuit low bank 1 sensor 1. Any suggestions? If I take it to the dealer, will it be covered? I cleared the code but it returned about 2500 miles later.

I personally wouldn’t hesitate to take it in to my dealer but I guess it all depends on your dealer / service manager - they shouldn’t have an issue with exhaust though. For them to refuse warranty service they would need to “prove” the exhaust caused the code….given the electrical gremlins on these trucks, good luck to them in proving that