I've been thinking about this issue for quite some time and I haven't been able to think of a good solution yet. I have been working on installing various electrical bits (gauges, alarm, lights, a/v gear, etc) in my Suburban. Because it's so many different items with wires that need to go through the firewall, I don't know how I'm going to run it all through and still maintain some form of water and wind resistance. Off-hand, I need to get 2 runs of 1/0 power cable or larger, 10 or so 18AWG wires, and 3-4 12 or 14AWG wire through, so it's a lot of wire! I've been thinking for the smaller wires that are mostly for gauges and such, I could use multi-conductor sprinkler wire or the like with terminal blocks on each side to break it out, but I've only seen 7-conductor 18AWG sprinkler wire. I still have some heavier gauge wires that need to go through and of course the monster power wires. The 1/0 wires I've been considering running under the cab to under the 2nd row bench seat where the floor takes a 90-degree jump up for the bed area of the cab, but I would need some very good waterproof bulkheads for that. Any ideas on getting massive amounts of wires into the cab?