Hi Guys, I currently have an ST185 and im getting a full exhaust from the turbo. I have the HKS 3" cat back exhaust, i however am getting an exhaust shop to make up a down pipe and front pipe (with high flow cat). Does anyone have any recommendations as to the size the pipes should be? should i keep the whole system 3" or should i get something along the lines of a 2.5" any ideas or recommendations would be greatly appreciated