I am thinking about picking up a set of headers for my 66 gto. The motor is stock and I've heard that headers may not actually be as beneficial as the stock manifolds. Is this the case? I was looking to pick up a bit of bottom end and, yes, a bit more grunt out of the exhaust. However if it is a big job (requires an engine pull right?) and I will lose power I probably shouldn't do it. Will I be losing power?