Your question can't be answered with only that much info. The cylinder head is basically the major restriction to the air pump we call an engine.The cylinder head will determine the intake side ( Carb, cfm,jetting etc..., manifold single plane,dual plane, hi-rise, tunnel ram, port size etc. cam type lift, duration/centerline, spring type and ,rocker type,ratio ... and on the exhaust side Manifolds,headers,large or small tube, long or short collectors, exhaust pipe diameter, h-pipe, muffler type Etc.....trans type and gearing,vehicle weight,rearend gearing and tire diameter, fuel octane, ignition type Whew! A whole lot to consider when you buy 1 part of the whole assembly. Everything must work together or you just bought parts.
What do you have and what do you expect from it?
Sometimes I just ramble on.....