[Modshack]

I don't know what your guys are doing, but it likely has nothing to do with the NPP circuit. You can easily wire a toggle to the #51 fuse using a fuse tap, some wire and a switch. This should not F with the computer at all. Since you're talking about 2 different things I suspect maybe their "Kill" switch wiring job is the issue...If you're doing a battery disconnect you would need some pretty big (Battery cables) wiring.