well,... you are right according to the formula..
Voltage= Current x Resistance
Well, they use reduced current leads nowaday because of all cars are equiped with radio and ECU. High current induce inteference to the radio that's why quite a comman problem in the old car need to get the thing connected to the dizzy/coil.... forgot what the thing called.
In the old days, car running coax leads(solid cooper) as spark plug lead other than the sillicon lead these days to get rid of the inteference and also coax lead tend to break easily... they don't like to be bend that much.
well, yeh,.. i always play around and testing this kind of things since i got a few spark plug leads from the wreakers to hack around and found them to work the best if they really really short.
I even custom made the cyclinder #4 lead to have double lead to a spark plug and I notice increase in performance. reason that i'm doing this is to make all of them having same resistance.
But I always carry spare leads with me incase somethings goes wrong