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It is for good reason that virtually every top professional engine builder relies on ARP Pro Series Head studs for their all-out competition engines.  Simply stated, there's not a better stud on the market today. 

ARP uses a premium grade 8740 alloy that is rated far superior to "aircraft" quality.  The ever-popular 8740 chromoly steel, for example, comes from the mill in four distinct grades. The lowest is “commercial,” which is followed by “aircraft quality.” ARP uses only the top two grades (SDF and CHQ), which cost twice as much, but provide the foundation for defect-free fasteners.

Following the basic shaping, material is heat-treated to desired levels. This crucial process is done entirely in-house to assure total quality control. ARP uses special vertical racks to hold each piece individually and assure complete 360° penetration. This is far superior to commonly-used methods of dumping items into a large bin and batch-treating.

The thread rolling operation (to MIL-S-8879A specs) is done after heat-treat, which accounts for a fatigue strength up to ten times higher than fasteners which are threaded prior to heat-treat.

ARP Head Studs are hands down one of the best products of its kind available on the market.

If you are rebuilding your engine, why not put in the best that is available?

The ARP Part # for these head studs is 260-4701

They Will fit the USDM 2002+ WRX, 2004+ STI, 2004+ Forester XT, and 2005+ Legacy GT