I know this has been discussed to death but not my situation. Running full msd ignition with 12v to the box. The coil is fed from the switch with the factory resistance wire still in. When I installed this 20yrs ago I called msd and they said leaving the resistor wire would be fine. If I recall right back then I had 8-9 key on volts at the coil and the engine ran good. Some reason I checked it today and get 3-4v and engine still runs good. If as is well known msd needs 12v to the coil why would it be running at all with 4? The meter is reading correctly. To test whether it runs "great" with 12 can I run P/N wire from the battery to the coil? If so do I leave the current wires attached while testing?