If you wanna go catless, thats up to you - and whether or not you have emissions. But as far as the x pipe goes, bassani and bbk are the last brands I would recommend to go with the Flowmasters. I've heard a lot of people complain about rasp with these brands. I would recommend SLP if you are going to go with the catted X, or Mustangtuning if you are going to go O/R. Both are great quality, and sound amazing with flowmasters.