That’s why the fastener experts at ARP have developed special bolts that are far superior to OEM hardware. ARP offers two styles of Flywheel/Flexplate bolts: High Performance and Pro Series. They are both forged from aerospace alloy and heat-treated prior to thread rolling and machining. Both feature an exclusive, flat, 12-point head design and larger than stock shank diameter for increased strength and improved flywheel register. The popular High Performance series is rated at 180,000 psi, and the premium grade Pro Series, originally developed for NASCAR Sprint Cup competition, has a 200,000 psi rating. Complete with washers and nutswhere applicable