battery box placement?

I put mine next to the fuel filler tube, put it as far back as you can on the passenger side.

The whole idea of relocating the battery is to swing 50lbs of weight from the front to the rear. Your taking battery (50lbs) and placing it over right rear tire to help plant it during acceleration. Because of the length of cable needed to reach front, most people use 0 ga welding cable. The large cable is needed to compensate for electrical resistance in the long run to the front. I would try to run the cable thru the interior as i've seen cable run underneath get damaged from road debris. Just a thought. Maybe inside metal conduit underneath may work. Hope this helps.

I ran my wires under the car thru my subframe connectors... That's a good way to keep them shielded from road debris. Then ran it up along the side of the engine bay by the exhaust in a heat-resistance sleeve made by Thermotec... It's pretty good stuff.