ARP CUSTOM AGE 625+ CYLINDER HEAD STUD KIT Subaru WRX/STI/Forester/Liberty (EJ20/EJ25)

ARP Custom Age 625+ Cylinder Head Stud Kit – Subaru WRX, STI, Forester, Liberty (EJ20/EJ25)

For Subaru EJ20 and EJ25 builds that demand the absolute best in fastener technology, the ARP Custom Age 625+ Head Stud Kit is the ultimate solution. Engineered for extreme cylinder pressures and brutal operating conditions, these studs are ideal for high-boost, high-power applications where standard 8740 or ARP2000 material just isn't enough.

Key Features

• Made from proprietary ARP Custom Age 625+ material with a tensile strength rating of 260,000+ psi
• Exceptional fatigue resistance and strength for extreme high-horsepower, high-boost engines
• Centerless ground and thread-rolled after heat treatment for maximum concentricity and fatigue life
• Undercut shorter studs help equalise stretch for more uniform clamping force
• Includes studs, 12-point nuts, hardened washers, and ARP Ultra-Torque fastener lubricant
• Stamped with ARP for guaranteed authenticity and quality

Why Choose ARP Custom Age 625+?

Custom Age 625+ is ARP’s strongest head stud material outside of proprietary race-only options. These studs are designed for the most demanding Subaru engines — including those pushing 35+ psi of boost, methanol fuel, or large displacement stroker kits. When your build leaves no room for compromise, this is the head stud kit to trust.

Vehicle Compatibility

• Subaru WRX (EJ20/EJ25)
• Subaru WRX STI (EJ25)
• Subaru Forester XT (EJ25)
• Subaru Liberty GT / Legacy GT (EJ20/EJ25)

Recommended for engines making over 500+ HP, running high boost, or built for sustained motorsport abuse.

Download Install Instructions (PDF)