Obtaining the optimum cylinder head-to-block sealing is especially critical in small displacement engines employing high compression pistons or power adders like turbochargers, nitrous oxide and superchargers. That's why ARP® head studs are popular among leading Sport Compact/Import racers. You should know that ARP® uses a premium grade 8740 alloy that is rated far superior to "aircraft" quality. Then, each stud is precisely heat-treated to 200,000 psi. Following heattreat, each stud is centerless ground to make it as close to perfectly concentric as possible. This procedure involves about ten very slight cuts and results in an exceptionally straight part. It's important to note that lesser quality studs are not even centerless groundthe material is thread rolled in bar stock form (mostly before heat-treat, when the material is easier to machine). Because ARP® studs are manufactured to such exacting tolerances, you will note that gaskets and cylinder heads literally glide into position and are perfectly alignedsomething that wont happen with inferior quality head studs. ARP® studs are thread rolled after heat-treat, which gives them about 1000% (that's ten times) better fatigue strength than those studs that are threaded prior to heat-treat. Premium parallel ground washers and Hex nuts (10 each) are also included with each kit. ARP is the leader in fasteners for racing and high performance. More winning teams use ARP fasteners than all others combined. Top quality, exact tolerances, the best materials and machining processes, and the ability to survive the rigors or racing and get you in the winner's circle make ARP fasteners the #1 choice.