when it was N/A i lopped the muffler off..bad idea, so raspy and loud..and slow.
now with turbo its 3" DP, 4" straight termining to a 90 after the crewcab. sounds good, no rasp, lots of whistle. havent heard it fully laoded yet though.
the truck felt much quicker when i put a muffler back on it vs str8 pipe when it was N/A. muffler was off an 06 duramax, 3.5" inlet and outlet...that was a big reducer lol
I am wondering how a tip would change the sound. my 4" is jsut the regular pipe, no tip on it, I am wondering if a double wall 5" tip would give it a deeper rumble with less "choofing" noise (not to be confused with valve chuff). you straight pipe turbo guys know what Im talking about. alot has to do with the firing order with have too though, you can clearly hear the pulses through the exhaust,