I have a 01 24v with a smarty and edge comp stacked, K&N intake and filter otherwise the motor is stock. It currently has a 5" exhaust to a turndown before the axle. I want to replace the exhaust with a nice full exhaust. I may add injectors and a little bigger turbo in the future. My question is would I be better off with a 4" or 5" exhaust. I tow alot so egt is my primary concern