I have seen dynos of different catbacks but don't think there is much of a difference. I do like the look of the stainless systems like Bassani and Borla. I remember reading up on this a few times in the past when a friend got a 03 Cobra new and then another friend got his 04. The T304 systems polish up nice which looks really sweet from behind the car. With a turbo car it's best to go with a straight thru design muffler but with a SC it really doesn't matter.