The Ford Focus is a compact car that replaced the Escort in 2000 and was redesigned in 2008. The second generation Focus is available in coupe and sedan versions. The Original Equipment Manufacturer's horn is an item that enthusiasts frequently replace with a much louder aftermarket horn. You'll need only a few tools to complete this relatively straightforward task.
Buy a horn kit. Direct replacement kits for the Ford Focus will have only one horn but many aftermarket kits consist of two horns. As an example, the Ford part number for the horn on a 2001 Focus is 2M5Z 13832-BB.
Locate the original manufacturer's horn. This varies somewhat by year but it is generally located under the hood near the bumper or driver's side fender.
Disconnect the power connector from the horn, take out the mounting bolt and remove the original horn. Most aftermarket horn kits include a high and low tone horn so you will not be able to use the original mounting location in this case. Find a sturdy location with minimal vibration and mount the horns with a fastener that is 8mm or smaller.
Splice the original pair of wires to the two horns according to the instructions for the new horns. The kit should include the connectors that you will need. Generally, you will splice a Y connection to the original pair of wires to produce two pairs of wires. You will then connect each pair to a wiring harness that is compatible with the new horns.
Test the new horn to ensure it works. If you are installing two horns, you may need test them one at a time.