ok, can somebody explain to me what's a 3 angle valve job and what it does, and what's a 5 angle valve job, what's the difference, and what about the porting and polishing=I know what it is, but how much you port on a GSR head and do I have to port bouth ports or jest the IM inside?=I know that this will make the GSR head flow better/right, so will it make the GSR head be close to the P75/PR3 head? and what else you do to the head? do I have to buy an after market IM in order to polish it, ? and if I do all that what should I exept from this MOD, will it gain HP all the way through RPM's or jest the top end? ?