For use on direct fire applications, the X4 has 4 channel output (4 cyl outputs). These are used in conjunction with LT10S and LT12S ECU's. We have chosen to now run external boxes rather than internal igniters as we once did, enabling us to run more advanced hardware on the boards to cope with our new IGBT Ignition boost function which is available on LT10S and LT12S ECU's as a standard feature.