I was messin around and just seein where the power wire would go through, and i realized that the firewall already in use for the factory wires was pretty much full, and i don't see how 1/0 is going to squeeze in there. But a couple inches to the right and one or two inches above it, theres what i'm guessing is an unused firewall hole. Its a rubber surround with a rubber filling. I tried to see where it came out on the engine side, and i couldn't find it. Does anyone know if i could (once i find the hole, as it was a little dark when i did this) puncture the rubber filling and take it through there?

If not, what should i do?

You could, but If you can, your best bet would be to drill a hole in a convenient place and insert a rubber grommet that way you have a good seal. If you do go this route, make sure you treat the hole with some kind of rust proof paint to prevent corrosion. Good Luck.

Oh ok, didn't think about that.. but how do i seal the excess space around the power wire? or is it not needed?

Find a grommet that makes a good seal around your power wire and drill the hole in the firewall as needed. You can find these at Home Depot, Lowe's, ACE hardware, etc... Same concept as all the wires going from the engine compartment into the cab of the vehicle.

Ok i think i got it, thanks for the help.