Just got my Hellroaring yesterday from UPS. All the wiring info/diagrams you need come with it. Buy the remote unit as well, it is all prewired and the instalation is straightforward.
You will need to buy the 2 or 4 gauge battery cable to link up with your primary battery, and the cable ends for the ground and starter terminals, but everything else comes with the kit. For an extra measure of safety, I also bought the 150 amp fuse, and I'm going to put it in the ground side, that way, if something shorts it out, it wil just be to ground, and not a dead short. Their website is very informative.
Also, Blue Sea Systems now has a very compact 150 amp marine style breaker that has a on/off switch on it, so that you can shut your amp(s) down with a via a switch at the end of the day, or if you need to do some work on them. The breaker is on their website if you want to take a look..www.bluesea.com