get at least 2 guage, and a decent battery, because when you need to start it, the electricity has to run 20 feet now instead of 5. I ended up putting a red top in my engine compartment for starting because I had some close calls. I have a yellow top in the trunk. Also make sure you get a good chassis ground. I drilled through my floorboard, and connected it to my frame, and make sure you use grommets any time you are going through sheet metal, especially the power wire. I can take some pics tomorrow if you like.
I agree with venom, on the location for the cut off, I've seen people actually cut through their license plate and put the kiil switch in the middle so it's always accesible, or you can put it in the key hole, and just rely on the trunk button or your alarm clicker to get into your trunk. The lock is easy to remove, and it would be easy to put back, and you would never have to drill. my $00.02