oh yeah stock mufflers are high flowin. Sarcasm

 

the only direct fit replacement I know of now, would be corsa cat back or mbrp cat back
I don't know of a direct fit muffler in 3.5 inch.
the problem with 3.5 inch is few muffler shops would have adaptors and tooling for their pipe
bender to make stuff to fit a 3.5 muffler.

 

Borla makes 3-1/2 race mufflers . . .

 

My OBX LT is working with my stock catback and it is flowing nice and not that loud what i am going to do is that i am going to remove the exhaust resonater and see how it will sound .

 

Your right...nothing high performance about mufflers that reroute the direction of exhaust gases via chambers...I bought Gibson Part# 615610, 3.5'' Mandrel bent stainless, straight through muffler...

 

most fo the guys that i ahve seen, weld in a 3.5" Borla XR-1

 

that looks good, have you installed it yet, how loud???

are your headers on yet?

 

I didn't install either, I just ordered a 2wd 2010 Sierra Ext Cab 6.2L w/3.73's should be here in 8 weeks. I'll post once installed on the new ride...