I have a apexi ws2 and its 2.3 inch piping. I want to get smsp header with smsp high flow cat, crower stage 2 cams with retainers and springs. How much is the exhuast going to hold me back? will i still see considerable gains from this setup? Should i go stage 2 or stage 1? i want something thats good for comfortable daily driving.

 

I'd go with nothing under 2.5". I have a 60mm exhaust and I'm planning on upgrading here soon.

 

its not that its so restrictive, but a bigger exhaust will make more power.