Car enthusiasts sometimes install air horns in their cars to produce a much larger and rounder sound than factory horns. Air horns typically come in sets of two or three horns, along with a compressor that sends air to the horns, giving them their sound. Before you begin installing horns in your car, consider where you will place the compressor and the horns themselves.
Prop open the bonnet of your vehicle. Disconnect the negative battery terminal by detaching the battery's terminal cable with a wrench.
Mount the air compressor onto a fender or firewall with the installation kit's mounting bolts. Use a wrench to tighten the bolts. Depending on the kit, you may have to drill a hole(s) through the reinforcement groove.
Connect the hot wire from the original horn to the air compressor with solderless connectors. Plug the ground wire into the air compressor beside the hot wire.
Mount the air horns outside of the engine compartment pointed at a downward angle so the various engine components don't muffle the sound. After removing the OEM horn, bolt the slotted bracket from the installation kit into the space left by the horn. You can install a third horn by the hood release lever mount but only after first removing a bolt from the mount.
Attach the air compressor to the fender or firewall and run tubing from the compressor to the horns. Secure the tubing to the wiring harnesses with nylon ties. Replace the factory 10-amp horn fuse with a 15-amp fuse. Test the horn to make sure it's working. If not, go back and check the wiring and the fuse.