All the MSD race and street ignitions that I've used , 404B to digital 7 non programable with a grid ,require you to eliminate the 12V resistor to the coil scope
The box controls the voltage pulse duration and voltage (WAY higher than 12.25V) to the coil for the multi spark feature scope
DON'T ask me how I know about the voltage to the coils whiney

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)