Scott....I answered you on the saleen club forum. first....do not put your phone number out there on forums. There are spam bots that will pick that up in a heart beat.
The stock tips on these cars are just magnaflow resonated tips....2.25" inlet...outlet is probably 3" - I would have to measure mine. they are mounted to a ypipe that is not a magnaflow piece. Any exhaust shop can fab that up for you.
For the NOS system, it is my understanding that there is just a pigtail harness that is needed. i gave you the guys name that i think has a few or can tell you what you need on the saleen site. I wont give out his contact info here.