ARP Subaru WRX EJ20 & EJ25 Head Stud Kit

ARP (Automotive Racing Products) is the world’s premier manufacturer of high-strength engine and driveline fasteners—head studs and bolts, main studs, rod bolts, and more—engineered and manufactured in-house from start to finish for race-proven reliability. With vertically integrated processes that include cold heading, machining, heat-treating, thread rolling after heat treat, and rigorous QA, ARP maintains aerospace-level certifications (ISO 9001 and AS9100) and validates every part for repeatable clamp load and fatigue resistance. Signature alloys such as 8740 chromoly, ARP2000, L19, and Custom Age 625+ deliver ultimate tensile strengths up to the super-alloy range, while ARP Ultra-Torque fastener assembly lubricant helps achieve consistent pre-load during installation. From street performance builds to professional motorsport programs, ARP fasteners provide precise fitment, superior metallurgy, and the durability needed to keep engines together at elevated cylinder pressures and...

ARP head studs replace factory head bolts with precision-machined threaded studs that provide more consistent and repeatable clamping force on the cylinder head gasket. Unlike head bolts that apply torque through both rotational and tensile forces, head studs allow the nut to be torqued concentrically on a stud that is already stationary, producing more even clamping load across the entire head gasket surface. Popular ARP Head Stud Applications ARP head studs are available for a wide range of performance and turbocharged engines including the Subaru EJ series, Honda K series and B series, Mitsubishi 4G63 and 4B11, Honda Civic and Integra, Toyota 2JZ-GTE, Nissan SR20DET and RB series, GM LS series, Ford Coyote and 5.0, and Dodge/Chrysler HEMI applications. ARP offers both 8740 chromoly and ARP2000 alloy head stud kits, with the ARP2000 material providing approximately 20 percent higher tensile strength for high-boost applications above 30 psi. Why are head studs preferred over head b...

This collection covers cylinder head components including head gaskets, head studs, and complete head assemblies for performance engine builds and high-output applications, serving vehicle owners and builders who need reliable components for maintenance, restoration, or performance enhancement. Arp head studs, cometic head gaskets, and edelbrock or afr cylinder heads are foundational brands in performance cylinder head work, providing buyers with the confidence that comes from sourcing from recognized suppliers with documented fitment data. Proper head bolt torque sequence and head gasket compression thickness selection directly affect combustion sealing integrity and engine longevity, and selecting the correct specification for the specific application is the most important step before any installation. Whether the goal is restoring OEM function, addressing a worn component, or improving beyond factory performance, this collection addresses each need with confirmed-fit parts. Popul...

This collection covers cylinder head components including head gaskets, head studs, and complete head assemblies for performance engine builds and high-output applications, serving vehicle owners and builders who need reliable components for maintenance, restoration, or performance enhancement. Arp head studs, cometic head gaskets, and edelbrock or afr cylinder heads are foundational brands in performance cylinder head work, providing buyers with the confidence that comes from sourcing from recognized suppliers with documented fitment data. Proper head bolt torque sequence and head gasket compression thickness selection directly affect combustion sealing integrity and engine longevity, and selecting the correct specification for the specific application is the most important step before any installation. Whether the goal is restoring OEM function, addressing a worn component, or improving beyond factory performance, this collection addresses each need with confirmed-fit parts. Popul...