2 1/2" or 3" exhaust?

[Anthony @ LG Motorsports]

Originally Posted by 0331Marine

Any issues with it being knocked down to 2.5 at the end of the cats then 3" the rest of the way back?

Depends on the setup of course.....I wouldn't try to make 1000 rwhp through a stock 2.5" muffler and say that it wouldn't gain anything by going to an aftermarket 3".. That being said we have tested the stock 2.5 vs our 3" mufflers but you are not really comparing apples to apples as it is a bigger size as well as a different kind of muffler.

Saying that on basically stock cars with headers, stock vs our mufflers there is 4-8 rwhp between them with no other changes being done to the car. We see about the same on the LS2/3 Corvette's as well when they go to the bigger muffler as well.

[Anthony @ LG Motorsports]

Originally Posted by Camaro Dude

Did you guys ever do testing on a modded, naturally aspirated LS3 application?

If so, what did you observe?

FI, it's a no-brainer, I don't need feedback on that. I'm only curious for normally aspirated and 3in vs 2.5, as per OP as well.

We did this comparison on a 2011 M6 Camaro a few years ago....it should be stated that we changed everything from the engine back. The car was using 1 7/8" long tubes with catless 2.5" mid section. The car was not running mufflers before and did not have mufflers on for the second test either. We changed the car over to our headers and went full 3", again catless for dyno testing. No changes in the tune or anything to the engine...same cam and heads were used and it was ran on the same dyno that same week (about 2 days apart).