9:1 compression. Standard bore. 2618 alloy forged pistons. These pistons include CP-Carrillo’s 51 series wrist pins and premium CPN ring set which includes a gas nitride steel top ring, taper hook groove second ring, and low tension oil ring. Forged from proprietary 4330M steel alloy for strength, fully machined, and shot peened for stress relieving, these connecting rods come bushed with premium silicone bronze bushings for full floating pins and top of the line CARR multiphase fasteners. This design retains the factory eighteen degree split line angle for proper ease of assembly.