How ' bout a super clean 12V source that is isolated from the battery itself? run a 2nd 7AH 12V battery on a switching relay and once the car is started, switch the power back to the 'line' power. could probably rig this up with 2-3 relays and some thought. Just need to figure out how to switch between power sources without any interruption, like a small bit of overlap or some type of switching relay that does that by design. The Sniper system doesn't take gobs of power to run and those 7AH batteries can kick out a lot of amps. Could rig a kill switch in there too if you want to run the sniper on auxilliary power the whole run. IIRC MSD draws an amp per 1000 RPM if that helps any.
