Stage X EJ25 2006+ Multi Layer High Performance Cylinder Head Gasket

This Stage X multi-layer head gasket is engineered for the most extreme conditions and is rated for use up to and over 800 bhp.

Instead of a conventional design, it uses a folded stopper layer. The gasket is thicker around the vital sealing areas, and this extra layer forms a much stronger barrier that keeps gases, pressure, water and oil where they belong, greatly reducing the chance of pressure leakage from the cylinders. It is highly recommended for any Subaru running above standard factory torque and power figures.

The gasket also has a nitrile rubber coating. It acts as a cushion that fills any imperfections in the cylinder head or block faces, helping the combustion chamber seal properly.

All Stage X head gaskets are die stamped rather than laser cut. Die stamping processes a large amount of material at once, so quality varies far less from gasket to gasket than with laser cutting, where each gasket is cut separately. Die-cut edges are also smoother and neater, while laser-cut steel leaves a sharper edge.

The gasket is designed to accept the larger 12mm and 14mm cylinder head studs. The standard head bolt, which joins the cylinder head to the block and provides the clamping force for the gasket, is 11mm thick with a relatively fine thread. It was developed for a mainstream engine producing no more than 320 bhp and was not intended for higher power. Stage X makes both 12mm and 14mm replacement head stud and nut kits. The studs are stronger thanks to their extra thickness and better material quality, and their coarser rolled thread allows far higher tightening. This gives a much higher clamping load between the cylinder head and block faces.

Reliability is key in any engine rebuild, whether for higher power or a simple repair or refresh. Choosing components carefully avoids repeating the job later.

Two gaskets are needed for one Subaru engine build.