does porting your valves 1mm over make a difference in overall performance and flow? i talked to josh from dh-racing and he said that using 1mm over valves was dangerous and didn tmake any real difference...........he siad that there is a risk of your valves hitting? i am using crower 297/287's, so i didnt that that i would have any problems with the valves hitting, i just thought it would help the head flow better! someone with some knowledge or experience with this please help! thanks also, does anyone know if i could send my bare head and all the internals i purchased to portflow, have them do the pnp, and then them assemble the head?