CP Piston & Ring Bore 99.5mm 8:2 CR WRX / STI Subaru Turbo EJ255 / EJ257 Models 2004-2021

Part #: SC7420. CP's forged pistons for Subaru WRX and STI models are a game - changer. They offer excellent ring seal, higher vacuum, less blow - by, long - lasting durability, and a significant boost in horsepower and torque across the power band. Thanks to lightweight forgings and CP's unique machining, peak horsepower stays consistent throughout the piston rings' lifespan. CP is all about top - notch engineering. They use the latest forging techniques and CNC machinery, and their strict quality control ensures a high - performance and reliable product every time. CP has some of the industry's highest quality standards and is part of Pankl Racing Systems, a high - tech group supplying to top racing teams and elite brands. You won't find a better piston for your EJ20 or EJ257. CP also offers optional coatings. The top coating reflects heat into the combustion chamber, increasing exhaust gas speed and scavenging. The skirt coating provides extra lubrication in extreme heat or heavy wear, reducing friction on the skirt. These coatings are applied to the whole set and add 4 - 6 weeks to the order time. Piston features include high - strength aluminum forgings, a super - lightweight design, full CNC machining and balancing to +/- 1 gram, an accumulator groove, double pin oilers fed from the oil ring, and wrist pins.

Using these CP pistons is straightforward. First, make sure your engine is properly prepared and clean before installation. Follow the standard procedures for piston installation in your Subaru WRX or STI EJ255 / EJ257 engine. When it comes to the optional coatings, keep in mind that they will take an extra 4 - 6 weeks to be applied, so plan your project accordingly. For maintenance, regularly check your engine oil levels. The double pin oilers help lubricate the pistons, but proper oil maintenance is crucial. Also, after long - term use or high - performance driving, it's a good idea to inspect the pistons for any signs of wear. If you notice any unusual noises or a drop in engine performance, it might be time to take a closer look at the pistons. Remember, these pistons are designed for high - performance, so treat them well to keep your engine running smoothly.