Just wondering about the compatibility of N/A and turbo exhaust systems. I was looking at the Bönez systems and both turbo and naturally aspirated are the same diameter (2.5"). Now I'm wondering if I could buy the N/A setup and simply change the downpipe and get a new cat if I ever swap my engine. If not what components (if any) of the N/A sytem could be reused in a turbo application?

http://www.rx-7.com/store/rx7/fcexhaust.html

 

ideally for a non turbo, a 50mm or 2 inch exhaust is ideal, while for a Turbo a 2.5 to 3 inch exhaust is ideal.

So you can use a 2.5 exhaust on a non turbo (the biggest I would use) but you may loose a little low end torque while increasing the top end. A 2.5 inch exhaust on a turbo is fine.