they will change the sound for sure, depending on the muffler they may give you a raspy sound. its def a better deal than the full x w/highflow cats, the kenne bell tech website say that cats only take 5 hp away and never found a "high flow cat" make any more power even on a s/c car.
I have pypes violators on the car now, I think I may have to go with some additional insulation in the trunk to get rid of a little interior noise. About how much performance improvement does the x-pipe provide?
from what I have gathered the X makes the sound more raspy vs an H. As far as performance you would be lucky to get a tenth off your times if that~ maybe 5hp/tq MAYBE.
__________________ 2003 REDFIRE COBRA #3938 of 5082 @ 05/27/2003 1 of 414
MGW Shifter, Stingers, JLT, SS Inserts, MM FLSFC & CC Plates, SS Lines, H&R Race springs, IRS Brace, MRT Hood Struts ME.com Member #29 - 400rwhp/380rwtq
i would also say about 5 hp and maybe 10 with a s/c. as for your interior noise the x with violators i think will be extremely raspy not to mention drone.