[Excaliber]

Removing the BALLAST RESISTOR will allow max battery voltage to the PRIMARY coil windings and depending on WHICH coil your using could burn out the coil.

I fail to see ANY connection between a high or low voltage coil being the cause of preignition or detonation. While the coil is running on max primary voltage the SECONDARY high voltage it may (or may not) provide to the plug is not a 'bad thing'.

Back to square one for me, I doubt the coil is the culprit.

Typical battery voltage is 14 volts. Typical primary coil voltage required is 7 to 9 volts. SOME kind of ballast resistor is needed to reduce primary voltage. Could be INTERNAL to the coil (can't be removed) or EXTERNAL (could be removed). Secondary voltage fires the plug, this could be as little as 20,000 volts or as high as a 100,000 volts (as most modern cars utilize).