Quote: 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
Never heard of cleaning up to flow better then stock. SOme aftermarket heads needed the some guide work, some are good out of the box. Others are aceptable to some others not so such. The RHS have no issues with cracking that would be the OE magnum heads
