ARP 2000 Head Stud Kit WRX/STI (EJ)

ARP high performance cylinder head stud kits are precision centerless-ground and thread-rolled to Mil-S-8879 specs. Their black oxide finish protects them from wear and corrosion, and ARP throws in hardened parallel washers for uniform load distribution and accurate torque readings. Keep your cylinders mounted solidly with a set of these ARP high performance cylinder head stud kits.

It is for good reason that virtually every top professional engine builder relies on ARP® Pro Series head studs for their all-out competition powerplants. Simply stated, there’s not a better stud setup on the market today. For openers, ARP® uses a premium grade 8740 alloy that is rated far superior to “aircraft” quality. Then, each stud is placed vertically in special racks and precisely heat-treated to 190,000 psi. This procedure ensures complete heat penetration and the results are far superior to those lesser quality studs from other manufacturers who just dump pieces in a basket and hope for the best. Following heat-treat, 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 (a very common industry practice). It costs a lot more to do it this way, because it’s tough on tooling, but the results are well worth the extra effort. You will also note that ARP® offers specially undercut studs for several engines. This procedure (done only to the shorter studs) more equalizes the “stretch” of both studs, which makes for a more consistent clamping force—and one that compensates for head gasket compression when the cylinder heads are installed. This helps prevent blown head gaskets, and assures optimum engine sealing!

*Suit 01-14 WRX/02-23 WRX STI