According to many post over the past few years, most of the NEW heads need seat and guide work before using them. They seem to need "cleaning up" to flow better than stock X and J heads also. Haven't there been issues with many new heads(RHS for example) cracking also?
Brad


Check out the Dorn's 69 Barracuda "Switchblade" in the Nov.2010 MCG
Check out the Dorn's refurbished 36 Ford in the Feb.2011 Street Rodder