ARP Head Stud Kit | 1989-1991 Porsche 944 S2 3.0L (204-4301)1989 1991 Porsche 944 S2 Head Stud Kit by ARP Factory head bolts can begin to stretch with higher cylinder pressures and cause a enough space between the block and head for combustion to leak out. Not only are you losing power, you are putting your cooling system and head gasket at risk. Replacing the stock head bolts with ARP head studs creates a super strong connection between the head and the block and will ensure a positive seal of the head