ARP Flywheel Bolt Kit Mustang Modular 4.6L 5.4L & SR20DET Flywheel and flexplate bolts play an important role in the performance and safety of both street and race cars, which is why the fastener experts at ARP developed bolts far superior to OE hardware. The flywheel bolts feature premium grade 8740 material that is rated at 200,000 psi tensile strength. ARP fasteners are centerless ground, heat treated prior to thread rolling and machining and designed to exceed the OEM fasteners in strength and durability. Optimum design, enhanced reliability and increased strength are the main attributes of ARP Pro Series fastener kits.