Coil ballast resistor

That will give you a very slightly lower voltage HT side when running. No practical difference in use IMO

that the resistance of the ballast resistor that is to be used with it is t o be 0.9 ohms, whereas my old one said 1.8 ohms. How relevant is this diffe rence?

Thanks. Having done some surfing on this topic with particular reference to my car I note that there is a range of resistors available, depending on w here the car was marketed. Weird that. Why should the country of origin dic tate the size of this resistor? I would expect the electrical effect to be the sole arbiter of this.

probably down to local ambient temperature, battery voltage is significantly down in colder climates.