CP Piston & Ring Set for Subaru EJ257 WRX STI- Bore (100mm) - Size (+0.5) - CR (8.5) - Set of 4

CP Pistons is well-known for making strong internal engine components for performance applications. This piston and ring set is built for the 2004-2012 Subaru Impreza WRX STI with the EJ257 engine. If you're rebuilding the top end of your engine, especially if you're looking to handle more power or are dealing with worn-out pistons, this set is a solid choice.

These pistons are forged from high-strength aluminum, which is a tougher material than cast aluminum and can better withstand the heat and pressure inside a performance engine. They feature a 100mm bore, which is a +0.5mm oversize, meaning they are designed to be used when the cylinders have been bored out to match. The compression ratio is set at 8.5:1, which is lower than stock and often chosen when building an engine intended for forced induction, like a turbocharger, to help prevent detonation. This set includes four pistons and the necessary rings to get your engine back together.

When installing these pistons, remember they are an oversize part, so your engine's cylinders will need to be machined to 100mm to ensure a proper fit. Always refer to the manufacturer's installation instructions for specific details regarding clearance and assembly. This set is not CARB approved and cannot be shipped to California.