One of the best upgrades for a 6.9 IDI when pushing higher than stock boost levels, or when rebuilding your engine. This kit is a genuine, American made ARP head stud kit using ARP 8740 Chrome Moly, rated between 180-210,000 psi tensile strength. ARP Material Guide: https://arp-bolts.com/p/technical.php "8740 Chrome Moly: Until the development of today’s modern alloys, chrome moly was popularly considered a high strength material. Now viewed as only moderate strength, 8740 chrome moly is seen as a good tough steel, with adequate fatigue properties for most racing applications, but only if the threads are rolled after heat-treatment, as is the standard ARP production practice. Typically, chrome moly is classified as a quench and temper steel, that can be heat-treated to deliver tensile strengths between 180,000 and 210,000 psi."
