CP Forged 99.75mm Bore / 9.0:1 Comp Pistons & Rings WRX / STI Subaru Turbo Models EJ255 / EJ257 2004-2021

Part #: SC7426. CP's forged pistons for WRX and STI models are a game - changer. They offer excellent ring seal, higher vacuum, and less blow - by. You'll get better durability and more horsepower and torque across the power band. The best part? The peak horsepower stays strong throughout the life of the piston rings. Thanks to lightweight forgings and CP's unique machining, this is all possible. CP is all about top - notch engineering. They use the latest forging methods and CNC machinery, and have strict quality control. This guarantees a high - performance and reliable product every time. CP has some of the highest quality standards in the industry. It's a part of Pankl Racing Systems, a high - tech racing group that supplies parts to top teams like in Formula One and companies like Ferrari and Porsche. 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. It reduces friction on the skirt by acting as a buffer to the cylinder. Coating options are for 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 forged pistons is straightforward. First, make sure to install them properly following the vehicle's manual or get a professional mechanic to do it. When using your Subaru WRX or STI with these pistons, drive as you normally would, but remember that they're designed for high - performance, so you can enjoy the extra power. As for maintenance, regularly check the engine oil level and quality. Change the oil as recommended by your vehicle's manufacturer. If you've chosen the optional coatings, keep an eye on the engine's temperature. In case of overheating, it might affect the performance of the coatings. If you notice any unusual noises or a drop in performance, have the engine checked immediately. With proper use and maintenance, these pistons will serve you well for a long time.