Ballast resisters

Are you sure? My many years of experience developing ignitions must be wrong, my cars are all going to stop running.

12V? The negative coil terminal peaks at about 400V, the high secondary would be open circuit, plugs on a mild engine strike at about 4kV. A ballpark arc voltage is 20kV per cm. Most ignitions can jump an inch, about 2.5 cm, that is about 40kV +.