When rebuilding an engine, there are several stock parts you wont want to reuse.
Stock headstuds stretch over time, and even more so each time they are re-tightened. If headstuds stretch, headgaskets can blow, and possibly even worse.
Racing puts more strain on an engine than it was meant to handle from the factory, it is normal for stock headstuds to stretch in high power applications.
Headstuds are a low cost item that can mean the difference between blowing a headgasket, or not. Use ARP Headstuds for your engine build.