Arp Head Stud for Porsche 911930 is stronger than the original fasteners and is intended to keep your race engine together under all conditions. Factory fasteners were not intended to be reused. When you torque a fastener, it extends to provide the necessary clamping force. If the fasteners stretch too much, they will no longer generate the necessary clamping force, potentially resulting in engine failure. When building your racing engine, remove your used original main bolts and replace them with a fresh new pair of ARP Head Studs to provide your engine with the necessary clamping power to keep all of your parts together in the hardest race conditions. Visit our website to buy the Arp Head Stud for Porsche 911930.