MSD Wiring w/ Trunk-Mounted Battery

MSD boxes tend to be sensitive to voltage issues.

I don't fuse the line as IIRC, there is a breaker inside the MSD box. You could put one inline if you like. MSD boxes usually draw about 1-1.5 amps per 1K/rpm.

Grounds definitely cause all sorts of problems with these boxes and other electronics like F.I. The large black wire goes to ground where I ground battery. You could also bring a clean ground wire forward and bus it up front.