All pistons are heat treated with a T-5 hardening and tempering cycle. All piston skirts are coated with a high-tech Molybdenum Disulphite coating for faster break-in time and increased piston life. Cast piston kits are gravity cast aluminum alloy (not forged) with 18% silicone content, which produces an extremely light but very strong piston. Forged pistons are forged from 2618 aluminum for superior strength and durability. Forged High Compression pistons improve power and torque across entire rpm range. Big Bore pistons increase engines displacement, torque, and peak horsepower. Forged Replica pistons are forged OE replacements. Replica pistons and all rings are OEM replacements.