When you add increasing amounts of turbo boost to diesel applications, you must provide an extra measure of security in the form of extra-strong head studs. ARP has introduced the new 625+ head studs. Custom Age 625+å material has a minimum rating of 260,000 psi tensile strength. They are engineered to provide the clamping force required to keep cylinder heads from lifting due to exceptionally high combustion pressures. You can torque these head studs up to 160 ft/lbs for extreme HP applications. ARP also offers head stud kits made from ARP2000 (220,000 psi minimum) for the Dodge/Cummins plus Chevy DuraMax diesel, Ford 7.3L PowerStroke diesel, and 6.0L PowerStroke. The stud kits include heat-treated chrome moly steel nuts (12-point) and parallelground washers. The studs are manufactured in ARPs Santa Paula, CA plant, with threads rolled after heat-treat to provide optimum fatigue strength. They are centerless ground to assure perfect concentricity. The ends of the studs are broached to facilitate easy installation. This feature also enables the cylinder head to be removed in tight quarters.