The Ford Focus is a compact, two-door car with a four-cylinder engine. Adding an amplifier to your Ford Focus is one of the best ways to improve the sound quality of the stock stereo. The stereo equipped in the Ford Focus has the audio cable connections on the rear, so you will need to splice the remote lead wire into the remote wire so that the amp turns on and off when you turn the key.
Plug the audio cables into the corresponding coloured connections on the amp. Cut speaker wire and the power wire the length necessary to reach from the amp to the rear of the stereo with wire cutters.
Strip both ends of the power wire and the speaker wire 1/4 of an inch from the top with the wire strippers. Connect the speaker wire to the remote lead connection on the amp and the power wire to the power connection on the amp.
Guide the audio cables, remote lead wire and the power wire to the front of the Focus along the passenger's side of the car. Conceal the wires under the floor panels.
Plug the audio cables into the corresponding coloured connectors on the rear of the stereo. Cut the yellow wire with the black strip. Strip the ends of the yellow wire 1/4 of an inch from the top and twist those ends with the speaker wire. Place a wire cap on the exposed wire and twist it to tighten it onto the wires.
Pull the floor cover back and remove the rubber plug from the firewall. Push the power wire through the hole. Open the bonnet and guide the wire to the positive battery connection. Connect the wire to the battery according to the owner's manual for the amp.