sub woofer cable
One option that you will have to consider at this point is the use of the braces for the inside, which, may result in a sturdier box in the end. You'll want to locate the tweeters above the woofer and "aim" them up at your ears if you want to achieve a realistic soundstage and stereo image. Although particle board looks a lot like fiberboard, its physical properties make it unfit for the car because Extreme temperature variations and humidity can cause particle board to chip, split, or warp in some way. Feed the power wire through the firewall. The RCA cable will run from the amplifier and connect to the RCA or preamp outputs on your radio.

custom car speakers
This will be a simple rectangular box. If it is behind or under a seat, make sure you leave enough slack to allow some movement. This is what the loudness circuit on a head unit tries to do. Disconnect the Battery.