when i get my 95 maxima back from my ex girlfriend i will be installing a system, the problem is, is there a simple way to run the power wire through the firewall or do i need to drill a hole? I will be using 4 gauge wire.

When you get it back, take a peek under the hood. 4AWG almost always will fit through a pre-existing hole in the firewall. I've never had to drill to get 4AWG power through. Once I stepped up to 0AWG, then I had to drill (at least on my current ride).

Just look for a grommet/boot somewhere that you may be able to slice and push the wire through. And don't forget to seal it up when you're done with some auto/marine sealant.

Didn't some of those come manual? if so there should be a clutch plate with nothing on the other side where you can easily drill through. make sure to use a grommet.