Swapping out GM performance muffler

brianc636 · July 8, 2019

Has anyone swapped out the muffler in the factory performance exhaust?

I was thinking I could use a Dynomax 17517 muffler and have an extension made to take up the difference in OAL. It just seems that 3.5” exhaust pipe in stainless is tough to find without paying out the nose for it.

lt1z · July 15, 2019

Any 3.5” straight through muffler will work but you will need to cut and weld pipe to connect it since the GM/Borla Muffler is longer then most aftermarket mufflers

brianc636 · August 24, 2019

Installed the 17517 muffler tonight and half assed mocked up the exhaust to see how it sounded.

At WFO it sounds about the same or a little louder but at cruising speeds it’s definitely louder.

I’m going to see if I can come up with some 3.5” tubing tomorrow locally and fully hook it up. If so, I’ll snag some video of it.

The new muffler is 1/2 the size of the GMPP unit.

brianc636 · August 24, 2019

Muffler differences. I put the GMPP muffler back on and had to order some 3.5” pipe since no one local seems to keep that size. I’ll report back once I get it all hooked up and routed out the back vs. just dumping out under the truck.

brianc636 · September 5, 2019

Got this put in tonight finally. Overall it’s a nice improvement. Sound follows the GMPP profile but louder more of the time. You can definitely hear the DFM or deceleration or something along those lines but zero drone at 70-80 MPH.

I need to upload my warm start clip and post here.