ARP 03-08 350Z / 03-07 G35 VQ35 Head Stud Kit ARP VQ35DE head studs feature an undercut design with 12-point nuts for optimal sealing and torque. Each ARP stud is made from 8740 alloy, rated higher than aircraft quality, and heat treated to 200,000psi. These studs are then centerless ground for perfect concentric design followed by thread-rolling. In addition, Nissan / Infiniti VQ35DE studs are undercut, which equalizes the stretch on the stud, making for more consistent clamping, and compensating for head gasket compression for improved sealing. Finally, they use a 12-point nut design and parallel ground washers for optimal seating and reliability.