GMC Performance Exhaust Experience

Denali4181 said:

Thinking of installing this on my 2019 RST. Is there any HP gained by installing?

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5hp & 5tq

Mad Maxx said:

5hp & 5tq

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Thanks. Getting it installed Wednesday.

GTNator said:

How loud is the GM Borla 6.2 combo on the highway? Is it noticeable when just cruising at 70MPH? Or is the cabin still whisper quiet until you hit the pedal hard?


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If you read my thread, combining the Borla touring with Kooks headers and high flow Y makes it ridiculously loud. And this is on a 5.3. Just advice should you plan on doing additional exhaust mods in the future. I need to find a quieter muffler to replace the borla because its just annoying at 70mph. But it is SOOO much fun to romp on the gas from a dead stop.

Got the BORLA installed. Very happy with it. Should be standard on the RST.

Denali4181 said:

Got the BORLA installed. Very happy with it. Should be standard on the RST.

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How is the noise inside any drone at all?

I tried just a muffler delete on my 18 rst and it was the worst drone I could imagine.

Have any pictures of the finish product. I would like to end it how the factory ends with nothing showing out the back

Which Borla system is everybody installing on their RST's? I hear there are two, one GM performance branded system made by Borla and the other Borla Touring system from Borla Everything I've read says both systems tube sizes are smaller than stock from the cats to the muffler, 2.75" or 3". Stock RST is 3.5". I couldn't find any aftermarket exhaust for my RST with 3.5" tubing.

1sikryd said:

Which Borla system is everybody installing on their RST's? I hear there are two, one GM performance branded system made by Borla and the other Borla Touring system from Borla Everything I've read says both systems tube sizes are smaller than stock from the cats to the muffler, 2.75" or 3". Stock RST is 3.5". I couldn't find any aftermarket exhaust for my RST with 3.5" tubing.

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I know that's weird isn't it. GM purposely chose 3" piping for the 5.3"L and 3.5" piping for the 6.2L so you would think there's some reasoning behind that because certainly it would be more cost affective do to 3" all around on a mass production vehicle...

Yet there are plenty of aftermarket exhaust systems for the 6.2L Silverado/Sierra platform that stick with 3.5" tubing.

I ended up picking up a lightly used Corsa Sport muffler from a GMC Sierra Corsa Part#14866, the muffler on that system is 3.5" In/Out, had a local exhaust shop weld it in place, remove the stock flapper, and left the stock resonator in place. Leaving the factory resonator in place is probably more like the equivalent to having a Corsa "Touring" exhaust versus a "Sport". I'm super happy with how it turned out, great sound, not obnoxious, zero drone and not over bearing on cold starts. The only thing I don't have is 3.5" mandrel bent piping, but it's not like I'm pushing any boost through it.

Before I stumbled across the lightly used Corsa #14866 muffler I was highly considering purchasing an entire Corsa #14866 kit and having an exhaust system just make it work and install it on my '15 Yukon Denali XL, I'm sure it could be done with minimal modifications that an experienced exhaust shop could handle.

LTRAutomotiveRST said:

How is the noise inside any drone at all?

I tried just a muffler delete on my 18 rst and it was the worst drone I could imagine.

Have any pictures of the finish product. I would like to end it how the factory ends with nothing showing out the back

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No drone at all with the GM BORLA system.