96-103" big bore conversion kit. 10.5:1 compression ratio. Converts the stock 96" Twin Cam to 103" with stock heads. Stock cylinders must be bored from 3 3/4" (3.750") to 3-7/8" (3.875") to accept the 103" big bore pistons. Comes with reversed dome forged pistons, Hasting rings, circlips and wrist pins.