ARP 247-4205 New Age 625 Head Studs 89-98 CUMMINSRunning a big single turbo or twins? Head studs are a must if you are pushing in excess of 45psi of boost. Why take the chance of ruining your day at the track or worse, doing permanent engine damage. With performance enthusiasts adding increasing amounts of turbo boost to diesel applications, ARP has provided an extra measure of security in the form of extra strong head studs manufactured from the firm's proprietary Custom Age 625+ material that has