CP Piston & Ring Set for Subaru EJ257 WRX/STI (Stroker)-Bore (100.5mm)-Size (+1.0mm)-CR (9.0)

This kit includes a set of four forged pistons and the necessary rings to match, specifically for your 2004-2012 Subaru Impreza with the EJ257 engine. These are designed for stroker engine builds, meaning they're intended for engines that have had their stroke length increased beyond the factory specification. The pistons themselves are 100.5mm in bore size, which is a +1.0mm overbore from the stock dimension, and they feature a 9.0:1 compression ratio. This setup is a solid option for those looking to build a more powerful engine.

CP Pistons is known for making well-built internal engine components. These pistons are forged, a process that creates a very strong and durable part capable of handling the increased stresses of a stroker engine. The 9.0:1 compression ratio is a good balance, allowing for good power output while still being manageable with pump gasoline in many tuned applications, though specific fuel requirements will depend on your overall engine tune. The +1.0mm overbore means these are intended for an engine that has already been machined to this larger bore size.