ARP Custom Age 625+ Head Stud Kit

Subaru WRX / WRX STI EJ20 & EJ25 2002–2021

Part #: 260-4704

Overview

The ARP Custom Age 625+ Head Stud Kit is a high-performance fastener solution designed specifically for Subaru WRX and STI models equipped with EJ20 and EJ25 engines. Engineered with advanced super-alloy materials, these head studs provide exceptional strength and durability, making them an ideal choice for enthusiasts seeking to maximize engine reliability and performance. Whether you're building a high-horsepower street car, a dedicated track vehicle, or an off-road machine, this kit ensures your engine's head gasket seal remains intact under demanding conditions.

Designed for both daily drivers and serious performance builds, the ARP Custom Age 625+ Head Stud Kit helps support increased horsepower and torque by maintaining proper head gasket clamping force. Its superior fatigue cycle life and tensile strength reduce the risk of head gasket failure, especially in high-stress applications involving boost, nitrous, or aggressive tuning. With resistance to atmospheric corrosion and oxidation, these studs offer long-lasting performance and peace of mind for your Subaru engine.

Key Features

The ARP Custom Age 625+ Head Stud Kit incorporates cutting-edge materials and manufacturing processes to deliver unmatched strength and reliability. Key features include:

• Constructed from Custom Age 625+ super-alloy, a high-performance material known for its superior fatigue cycle life, tensile strength, and toughness.
• Complete resistance to atmospheric corrosion and oxidation, ensuring longevity even in harsh environments.
• Precision-machined threads and surfaces for optimal fitment and consistent clamping force.
• Engineered through advanced manufacturing and testing processes to meet or exceed OEM standards.
• Designed specifically for Subaru EJ20 and EJ25 engines, including WRX and STI models from 2002 to 2021.
• Ideal for high-performance builds, forced induction setups, and engines subjected to increased stress.
• Less expensive than other super-alloy fasteners, offering a cost-effective solution without sacrificing quality.

Construction & Design

The ARP Custom Age 625+ Head Stud Kit features high-strength, super-alloy steel fasteners that undergo proprietary manufacturing and heat treatment processes. The studs are precision-machined to ensure perfect thread engagement and consistent clamping force across all fasteners. Their one-piece design and advanced alloy composition provide excellent fatigue resistance, making them suitable for high-stress applications. The corrosion-resistant finish adds durability, ensuring the studs maintain their integrity over time, even in demanding environments.

Installation & Fitment

The ARP Custom Age 625+ Head Stud Kit is designed for straightforward bolt-on installation for experienced mechanics and enthusiasts. Installation involves removing the cylinder head and replacing the factory head bolts with these high-strength studs. No cutting, drilling, or special modifications are required. Proper torque specifications provided by ARP should be followed to ensure optimal clamping force and sealing. It is recommended to use ARP assembly lube during installation to achieve the correct preload and prevent thread galling.

• Compatible with Subaru WRX and STI models equipped with EJ20 and EJ25 engines from 2002 to 2021.
• Designed for high-performance applications, including turbocharged and heavily modified engines.

What's Included

• Complete set of head studs for both cylinder heads
• Necessary nuts and washers
• Installation instructions

Ideal For

• Performance enthusiasts building high-horsepower Subaru engines
• Turbocharged or supercharged setups
• Engine rebuilds requiring high-strength fasteners
• Track and drag racing applications
• Long-term durability in demanding conditions