As for the effects on what ever, there should be NO changes, that is the purpose of the ballast to maintain a constant primary current with variation in engine speed. That means a stable ignition with no variations related to engine speed.
The coils Impedance is mainly inductive reactance XL with very little Resistance. XL is dependant on frequency which is engine RPM.
Impedance is a combination of the XL and R of the coil
Primary winding current will be determined by the voltage divide by the impedance of the coil Z.
I(primary)=Volts(12v) /Z
So as RPM increases the XL increases and primary current will decrease.
High primary current at idle and low primary current at higher RPM
By adding a resistor the total impedance will become more stable and not vary as much with RPM.
This is what I remember from ENGE 121
I would recommend following the directions from Accel.
I had a 360 in an 81 IMPERIAL with a super coil. I ran it with the stock ballast resistor and never had any problems.
Im guessing if you don't have enough external resistance and then idle the car a lot primary current will be high and could potentially over heat the coil, shortening it's life.
The ECU is a transistor that grounds the coil to give you the high voltage spark. The primary current has to go to ground through it. It will have some limit to how much current it can safely handle but I don't know what that is.
