is 100mm (4inch) exhaust too big for stockish FD?
 

I am looking get rid of a homemade exhaust that came with my car and was wondering what's the ideal exhaust diameter for a mildly modded FD.

Currently the car has rx7 store dp, ebay intake. Thanks.

No such thing has to big on a turbocharged car. Now to booming for street use is up for debate :) Keep in mind you're probably going to want to port your wastegate and do some fuel mods...