ARP Toyota 2JZGE/GTE 1JZGTE Main Stud kit

These are not for your cylinder head
Main studs hold your crankshaft in place. As you make more power, and rev higher than your engine was designed to rev from the factory in stock trim, you start to push the limits of the factory fasteners.

Factory fasteners were not designed for performance use. The material chosen by the Original Engine Manufacturer for your engine's factory fasteners was chosen to meet the criteria of a normally driven consumer vehicle at the provided stock horsepower and rev limit. The material is not optimum for a high revving, high heat, high power, race car.

The factory fasteners were also not designed to be reused. Every time you torque a fastener, it stretches to perform the proper clamping force. If the fasteners stretch too far, they will no longer provide the required clamping force, and can lead to an engine failure. When you take your factory engine apart to build it into your race engine, discard your used factory main bolts and switch to a brand new set of ARP Main Studs to provide your engine with the proper clamping force required to keep all of your parts together in the harshest race environment.
ARP Main Studs are stronger than your stock main bolts.
You should not reuse fasteners multiple times (especially stock ones) - they stretch
Quality Fasteners are required to keep everything where it belongs in your engine.

ARP Main Studs are manufactured from 8740 chrome moly steel, heat treated in-house to 190,000 psi tensile strength, and precision J-form threads rolled after heat-treat to create a fastener that has threads 1000% stronger than others!

There are many important reasons to use ARP main stud kits, including the elimination of main cap walk and fretting, as well as protecting the threads in your engine block.