If the musty, mildew smell is present in your interior, chances are there’s mold hiding underneath carpet padding or growing in your headliner. It might be worth considering a Smoker’s Remedy with OZONE or similar deodorization procedure to see if the smell subsides. Alternatively, schedule a...
Pick a continuous path for the wires to flow through the car, hopefully with a minimum of pulling up carpets or pulling down headliners. The advice in “Gauge Your Wires” [Hack #3] applies here—you want to pick a wire thickness that can handle all your devices. If you figure that ...