ARP Main Stud are made out of premium 8740 alloy rated far superior to aircraft quality, heat treated to 200,000 psi, thread-rolled after heat treat (which results in a stud that has 2000% (20 times) better fatigue strength than studs that are thread rolled prior to heat treat. Using studs will make it much easier to assemble an engine (especially a racing powerplant which must be serviced frequently and quickly!) with the cylinder head and gasket assured of proper alignment. Studs Provide more accurate and consistent torque loading ( When you use bolts to secure the head, the fastener is actually being twisted while it’s being torqued to the proper reading. The bolt is reacting to two different forces simultaneously.