Discussion Starter · #1 ·
Is there a noticable performance difference on 2" vs 2.5" for the ZZ4 motor? I am running the 2.5" pipes and am thinking of installing the 2" pipes for more ground clearance . I know that you don't necessarily get increased performance when going to larger pipe size due to some needed back pressure. I don't remember the diameter of the exhaust valves on the zz4 motor but read somewhere that the exhaust should match the same diameter or performance may suffer (of course all bets are off if nitrous or a blower is used or if one just uses the large pipes for just hi rpm racing but my BH is basically a street bike that ocassionaly sees hi rpm (usually on the hiway. ha).Is the 2" exhaust pipe the ideal size for the zz4 motor?