From Drag to Endurance CP pistons have proven their quality in the racing community. These pistons for the 08-10 Evo X are avialable in 86mm stock bore, 86.5mm w/ 0.5 overbore, or 87.0mm w/ 1.0mm overbore and retain a 9.0 compression ratio. These pistons are designed for high horsepower applications and are much stronger then OEM due to the forging process CP uses. The CP pistons for the Evo X 4B11 are an excellent choice for your engine build.