Buick Stage II main bolt kit ARP 123-5202 The ARP High Performance Main Bolt Kits are forged from premium 8740 chrome moly and all the bolts feature and generous under-head radius and heat treating for utmost reliability. The threads are rolled after heat treating, which makes them about 1000% stronger than most other main bolts. These bolts are nominally rated at 180,000 psi, and are a premium replacement for any OEM fastener.
