ARP Head Stud Kit
Fits 2002-2005 Subaru Impreza WRX 2.0L Turbo (EJ205 Engine)
Fits 2006-2014 Subaru Impreza WRX 2.5L Turbo (EJ255 Engine)
Fits 2004-2020 Subaru Impreza WRX STI 2.5L Turbo (EJ257 Engine)
Fits 2004-2006 Subaru Baja 2.5L Turbo (EJ255 Engine)
Fits 2004-2013 Subaru Forester XT 2.5L Turbo (EJ255 Engine)
Fits 2005-2012 Subaru Legacy GT 2.5L Turbo (EJ255 Engine)
Fits 2005-2009 Subaru Outback XT 2.5L Turbo (EJ255 Engine)
Obtaining the optimum cylinder head-to-block sealing is especially critical in small displacement engines employing high compression pistons or power adders like turbochargers, nitrous oxide and superchargers. That's why ARP head studs are popular among leading Sport Compact/Import racers.
You should know that ARP uses a premium grade 8740 alloy that is rated far superior to "aircraft" quality. Then, each stud is precisely heat-treated to 200,000 psi. Following heattreat, each stud is centerless ground to make it as close to perfectly concentric as possible. This procedure involves about ten very slight cuts and results in an exceptionally straight part. It's important to note that lesser quality studs are not even centerless ground—the material is thread rolled in bar stock form (mostly before heat-treat, when the material is easier to machine). Because ARP studs are manufactured to such exacting tolerances, you will note that gaskets and cylinder heads literally glide into position and are perfectly aligned—something that won't happen with inferior quality head studs.
ARP studs are thread rolled after heat-treat, which gives them about 1000% (that's ten times) better fatigue strength than those studs that are threaded prior to heat-treat.
Prevent blown head gaskets and ensure optimum sealing!
