ARP Subaru WRX EJ20 & EJ25 Head Stud Kit - 260-4701

ARP Head Stud Kit — Subaru EJ20 / EJ25 DOHC, 11mm (260-4701)

The clamping force required to keep cylinder heads from lifting under higher combustion pressures. On a boosted EJ that's the whole job — head lift is what kills factory gaskets, and no gasket fixes a fastener problem.

Manufactured from ARP2000 alloy, rated far superior to "aircraft" quality, with each stud placed vertically in special racks and precisely heat-treated to 220,000 psi. That vertical racking ensures complete heat penetration rather than dumping pieces in a basket and hoping.

Threads are rolled after heat treat, giving roughly 1000% better fatigue strength than studs threaded before heat treat — a common practice elsewhere. Centerless ground to assure perfect concentricity, so heads and gaskets align properly during assembly.

Includes 12-point nuts and hardened parallel-ground washers for even load distribution and accurate torque readings.

Specs: 11mm, ARP2000 material, 220,000 psi tensile strength.

Fitment: Subaru EJ20 and EJ25 DOHC — 02-14 WRX, 04-21 STI, 04-13 Forester XT, 05-12 Legacy GT, plus EJ25D, EJ251, and EJ253 naturally aspirated applications.

Pair with an MLS head gasket. MLS needs consistent, even clamp load to seal properly, and that's exactly what a stud kit delivers where a torque-to-yield factory bolt can't.

Worth doing on any EJ that's open. This platform has a long history of gasket failures, and if the engine is apart, this is the cheapest insurance against doing the job twice.