CP Piston & Ring Set for Subaru EJ257 WRX STi - Bore (100.5mm) - Size (+0.25mm) - CR (10) - Set

Forged from high-strength aluminum alloy, these CP Pistons are built to handle the demands of a performance Subaru EJ257 engine. This set is specifically sized at 100.5mm bore and +0.25mm over, designed to replace your stock pistons with a well-built, durable component. The 10:1 compression ratio is a notable change from stock, aiming for improved power output when paired with appropriate tuning and supporting modifications.

CP Pistons are known for their robust construction, utilizing advanced forging techniques to create pistons that are both lightweight and incredibly strong. This strength is crucial for engines that see higher boost pressures or more aggressive driving. Each piston in this set is precision-machined to ensure a proper fit within the cylinder bore, which is essential for maintaining good compression and preventing blow-by. The included rings are matched to the pistons for optimal sealing.

This piston and ring set is intended for engine rebuilds where performance and reliability are key. It's important to note that this part is not CARB approved and cannot be shipped to California. Proper installation, including correct ring gap, piston-to-wall clearance, and cylinder honing, is critical for the longevity and performance of these components. Always refer to the manufacturer's detailed installation instructions for best results.