Custom designed taller pistons have less piston slap. Rings have been spaced apart for better cooling. Pistons have .020" wrist pin offset to take load off the intake side. Forged pistons are more durable and collapse less than factory pistons. Lubrication holes in the skirt of the piston designed to lengthen piston skirt life. Friction-resistant coated pistons. Gains 6-7 hp and even more for motors down on compression. A must have for motors with over 1500 miles on stock pistons. No EFI controller required. Includes pistons, rings, circlips, wristpins, cylinder bolts, cylinder spacer, longer alignment pins, and two base gaskets.