Depends on the catback. If you have a MAC, Flowmaster, Magnaflow (not magnapacks), or Dynomax you can get away with the catless x-pipe. All the rest sound TOO loud IMHO. I'll get a good clip of my '98 GT with the LM! and offroad X-pipe to prove my point, lol. If you like NASCAR sound it's great I guess...or for scaring old people in cars next to you..lol.