How about a list of tools that we all have for installing? I just work out of my garage on my own car, but...
about 15 drawers full of all kinds of electrical connectors everything you would ever want, self tapping screws, replacement clips for my car that I stocked up on, small stockpile of other screws and heatshrink
good pair of wire strippers, big channel lock crimpers for putting terminals on large gauge wire, greenlee multimeter, test lamp, really good ratchets and full sets of metric and standard sockets, good quality screw drivers, small butane torch for quick soldering jobs, weller soldering iron, several hundred zip ties, several feet of wire loom, and of course a small fortune in various power, speaker and accessory wire
also can't forget the craftsman power drill and air compressor with all the tools.