This CP piston and ring set lists a bore of 89.0mm for the Mitsubishi 4B11 used in the Evo X and is supplied as a set of four custom pistons. The product description identifies its application to the 4B11 Evo X and specifies the bore size and set configuration for accurate replacement or engine work using those dimensions.
CP Piston & Ring Set for Mitsubishi 4B11 Evo X - Bore (89mm) - Set of 4 (Custom Pistons)