W5GX pointed out the thread, the chart would make you consider 10 gauge. Triple-insulate your firewall -through wires, and use water-tight holders for the fuses on the engine-compartment side. There are a couple of other considerations: 1. Mount everything such that it cannot move much, or be moved by airbags. To do this, you will probably be doing some drilling inside the vehicle- at least we hope that you mount the microphone holder such that you are not sending a random PTT with a somewhat dead carrier. For the drilling, invest in a good set of Cobalt Steel, not just Z.Nitride coated bits. These are less likely to be brittle and fail on curved metal ( as in under seats- it almost all is ). Be sure to watch the back of whatever you drill- air bags can inflate if you hit a wire- and can cost plenty. Watch for top-curtain bags when the speaker is mounted, or the antenna wire routed. Remote cabling- be sure your Kenwood kit is sufficiently long ( including ups and downs- eg. alongside carpet, kick-boards, or headliner ). Consider an extra run of Category 5 or 6 8-conductor or shielded 8-conductor stranded cable and the appropriate RJ-45 or Kenwood PG-5H made as an adapter. For the speaker, the Kenwood TM-D700a could sound better in my opinion using the Yaesu speaker ( approx. 4 inches on a side ) with the red square noise-filter button. You should be able to get single channel audio to sound good without changing a plug size that way. You really do not want to try to listen to two channels at once, as transmitting based upon that audio can get others confused. If you must, get two of the Yaesu speakers and an extra switch to easily turn one off rather than turn the knob. Finally, if you can still get a Brute-Force filter for your alternator and battery supply- it made sense to me. Other amateurs may say that if the vehicle is noisey, this is like a doctor covering the symptoms. I would have to agree, but that they know it can help. If you just spent around $700 for the rig, another $25.00 to $35.00 to keep the power-line clean seems like cheap insurance to me. These filters can be home-built, for better serviceability. Or you can check with Motorola or Kenwood for a pre-built unit. If you are interested in fldigi, etc. then also see the K5URU / www.wlhkj.com info first.