ARP Head Stud Kit for Audi 5-Cylinder 10-Valve Diesel

It’s no wonder virtually all top professional engine builders rely on ARP Pro Series head studs for their competition engines. As already mentioned, there is no better stud system on the market today. ARP uses a premium grade 8740 alloy that is many times stronger than aircraft quality material.

Each stud is placed vertically in special fixtures and precisely heat-treated to 200,000 psi. This procedure ensures complete heat penetration. The results are vastly superior to the inferior studs from other manufacturers that merely dump parts in a basket and hope for the best. After heat-treatment, each stud is centerless ground, achieving nearly perfect concentricity.

This process involves approximately ten very subtle cuts, resulting in an exceptionally straight part. It's noteworthy that lesser-quality studs are not even centerless ground. The material is threaded in bar stock form (usually before heat-treatment, when the material is more accessible to the machine).
Because ARP studs are manufactured to such exacting tolerances, you’ll notice that gaskets and cylinder heads literally slide into place and are perfectly aligned—something that won't happen with inferior head studs.