[Bobcat]

Byron ... you should be more concerned with voltage spikes than current , as voltage fluctuations/transients are what kill the MSD system ... and other electronics . This normally happens , for example , if you jump start your car ( connecting/disconnecting the jumper cables ) or switching some accessories on and off . This causes your voltage to do weird things ( transient spikes ) that can hurt the MSD . For lack of a better description , this is a noise filter ( surge suppressor/clipper ) and it must be located such that it filters the power going to the MSD system .
You could probably get one at the local Radio Shack ( around 25 k to 50 k microferrads and 16 vdc ) , but in all honesty , the MSD unit is such a neat package and comes with instructions and mounting hardware , it`s hard to beat .