The instruction sheet in the written portion specifically recommends installing the units without the resistor in place. Clouding the issue are two schematics of which one shows the wiring with a resistor and another without the resistor. I install the Pertronix ignitions without the resistor as per the written part of the instructions and (cross my fingers) haven’t had any trouble yet. I do maintain the factory specified spark plug gaps though and firmly believe that the factory spark plug gaps are more conducive to having the units last longer.