hay guys as some of you may know i want to put an exhaust system on my vs and a cold air intake with extractors. now for extractors im thinking pacemackers cai not too sure if i should get a Genuine holden commodore one or an aftermarket one.i want the one wich will produce the most proformance

. and for the exhaust i thinking cat back but i dont know if i should get a 3 inch or a 2.5 inch. btw its a vs s pack with IRS and its a manual.