for turbo,you should have 3 inches pipes from down pipe,highflow cat,midpipes to the muffler the inlet of your muff should be 3 inches too.. get a jasma certified muffler so you'll love the sound and not annoying noisy.. yet the performance is still there..the outlet of the muffler should be around 5-6 inches. 3 inches is the best size for turbo protege.. for NA is 23/8inches.