The factory head bolts are rather soft which renders them not as dimensionally stable as the hardened ones. Soft head bolts are prone to stretch as they are torqued. Heat cycles from running the engine, combined with the less dimensionally stable stetched bolts, contribute to the head bolts loosening. It was my practice and was told from several engine guys to NEVER LocTite the head bolts due to having false torque values. (You think the bolts are tight but aren't, contributing to a leaking head gasket. This, in turn, causes lean runs which destroys your engine.)

JMP's head bolts are harder and are less prone to bolt stretch when tightened. Also, being more dimensionally stable, the bolts do not expand and contract as much during heat cycles, which would contibute to them loosening. Another plus is that the hardened head bolts are not as easily rounded off with the hex key. Rounded off head bolts are a *itch to remove....[:@]

I hope this helps...

Kevin