MSD 8225 HEI Ignition Coil The coil is a direct replacement of the stock coil and offers increased spark energy when used with the MSD HEI module, PN 83647 The coil features special low-inductance, high-temperature windings which charge faster to give you increased spark energy at high RPM OBD II and CARB approved and legal for use in all states Coil mounts directly in place of factory style with improved performance