TBH i don't know the exact details, but after looking at the EMS5 i had and readed the destructions that how it does it both advance and then retard. The EMS5 is a much better unit, the EMS6 only allows retard i think. The EMS5 can be used with an injector driver "PIC" it was on mine. You adjusted the RPM/advance/retard via a series of screws