voltage drop issue.

Something I have not yet figured out today as I just wired it up. I use the Ice Ignition 7amp box and coil and just bought there voltage boost box which puts a constant 16 volt to the coil(inductive spark). Its wired thru a toggle and when I switch it on my voltage drops 2.5 volts on my voltmeter and the switch wire to my 7amp box, but not the battery. Still need to do some more checking tomorrow, but any idea what areas I should be looking? Maybe that box just pulls a lot of current? Thanks

wire it up through a relay, so it pull straight off the battery

ok, ill give that a shot.

Took another look at the wire diagram and noticed no switch wire to 7amp ignition box when using a booster. So i wired the booster with a switch wire and the ignition box without. It worked and work really nice. 16.75v at the coil now. Only thing i can figure is that the negative coil wire must feed the current to the ignition box to turn it on. Go figure. Ignition box turns on without the switch wire hooked so no voltage drops any where. Cool!