Pardon my ignorance (I don't have a 1200GS), but I thought the coils were built into the plug caps and therefore a long way from the area of the battery. Or am I wrong and that only applies to the 1100/1150 range ?
I suppose you could get interference from the fuel pump, Brake Servo pump and other electronics in that area but nothing high frequency I'd have thought.
I wait to be corrected.
Bob.