The CR550 is for Big  Bore M8s 143 and bigger 11.5-12.5:1 compression. 124 and 128 engines will demand a minimum of 12.1 compression

  It has proprietary  lobe design with transition ramps to help comntro; lofting at max lift and  valve bounce on on the closing ramp

    giving it the ability to turn High RPMS    with Maximum results