u sure the cai and the evo both didn't gain 13 horses?...evo on it's own can't gain 13 horses...nice gains offa just i/e tho...o...and to answer the thread...muffler by itself gonna sound like trash...but u can always get the muffler and get custom piping...thas what i did...and it sounds pretty nice...just don't really like the looks anymore...got like a 4" tip...i was 16 and dumb...i got 2.25" piping...anything bigger and it's more detrimental...cuz u lose too much backpressure...unless u go turbo...then get 2.5" or 3"