Mahle PowerPak 99.75mm Bore Piston and Ring Kit Subaru WRX / STI EJ25 2004-2021

Part #: 930285227. Mahle's PowerPak piston assemblies are a race - tested combo that includes forged pistons, rings, pins, and wire locks. The pistons are carefully hand - deburred and coated with dry phosphate, which safeguards against ring micro - welding and pin galling when you first start up your engine. Mahle has also added its unique Grafal anti - friction coating to the piston skirts for better performance. The set comes with low - drag rings, steel pins, and round wire locks. Specs: Mahle MS Piston Set EJ25 99.75mm Bore 79.0mm Stroke 130.4mm Rod 23mm Pin - 10cc 8.5 CR Set of 4.

Using this Mahle piston and ring kit is straightforward. First, make sure your engine is clean and ready for installation. Carefully place the pistons into the cylinders, following the correct orientation. Ensure the rings are properly seated in their grooves. When starting your engine for the first time, take it easy to let the dry phosphate coating do its job of protecting against wear. As for maintenance, regularly check the engine oil level and quality. If you notice any unusual noises or performance issues, have the engine inspected. Keep the engine clean and avoid over - revving to prolong the life of the kit.