Alan-
Exhaust gets more restrictive as it flows out. The bigger it gets on the way out the better. 3" cat back would be best for the power you want. You could squeak by on 2.5 but the Bassani is only 2.25. My set up is a 3" cat back to a 2 x 2.5 and then out. So doing some kind of crazy math it comes out to 6" of flow coming out the back going into 2 x 2.5.
