IAG Performance / ARP 14mm Head Stud Set Most Subaru Models

The IAG / ARP 14mm Head Stud Set is engineered specifically for high-horsepower Subaru EJ engines where extreme cylinder pressures demand maximum clamping force. By increasing the stud diameter to 14mm, this system significantly improves load capacity, helping prevent cylinder head lift and the head gasket failures commonly associated with high-boost applications.

Compared to standard-size head studs, the oversized 14mm design delivers superior strength and more consistent clamping under extreme operating conditions. This makes them an essential upgrade for engines targeting high boost levels, competitive motorsports use, or Fire-Lock™ head gasket systems that require increased clamping force.

Installation of the 14mm head stud set requires engine block and cylinder head machining. The engine case must be drilled and tapped to accept the larger studs, and the factory locating dowels must be split or modified accordingly. Additionally, the cylinder head stud holes must be enlarged to provide proper clearance for the 14mm studs.

This head stud set is intended for fully built engines and professional machine work, ensuring the strongest possible head-to-block sealing for high-output Subaru EJ builds.

Includes:

• (x12) ARP2000 14mm x 1.5mm Head Studs
• (x12) ARP Washers
• (x12) ARP Nuts
• (x1) ARP Fastener Assembly Lube

Install Requirements:

• Use head gaskets with 14mm stud provisions or drill head gaskets to clear the larger 14mm head studs for fitment
• Splitting the OEM locating dowels
• Drilling and tapping the engine case
• Drilling out the cylinder head stud holes for 14mm stud clearance

Installation Instructions