What is the difference between a stock N/A muffler and a T2 muffler?? Just wondering because I found a wrecked T2 with 30000 miles and a lot nicer cat-back then mine https://www.nopistons.com/forums/pub..._DIR#>/dry.png The N/A is round, where as the T2 is more rectangular, but other then that they seem the same.

yep, t2 has larger cans, it will bolt up to an na just fine

Any difference in flow or sound??

might be a little better flow

Would it also matter in being a 6-port(if he has a 6-port) and the regular 4-port turbos?

I do have a large SP 6 port with RB headers and a Dynomax race 16"x3.0 I put the T2 catback on this car and the sound level is a lot quieter, but seems faster.