Found a mech. who said he would run pipe, any size, from the cat back. my question is, what size pipe does an expenxive Jun or Greddy cat back use? And is there any performance difference in a nice muffler with this guy welding on the same size pipe, as a catback would have? will it be loud and blow smoke or what? Who went the do it yourself route? let me know. Did you replce cat with test pipe or what? thanx a sheeat load guys!

 

2.5 or 3 if your gonna turbo it. It will only blue smoke if your car burns oil, and it depending on what muffler you buy, the louder it will be.