hi all, i am looking into buying some leads for my 98 terzo and know of a set for sale for a 97. the make is nitso and they look excellent quality but they have like a secondry wire running off each lead looks like some kind of ground wire? if this is what it is where would these be ground to on the engine? i would assume that at least two ground points would be needed one for each side. also why do some leads have this extra wire?cheers richard.