Re: horns

You don't say what car you have. The trick with air horns is that
they are very power hungry - even if you have a relay in the
horn circuit already, you probably need to add a new circuit
to drive the compressor.

My preference for a car that used the newer style Lucas/Clear Hooter
horns (without a dome) is to buy Hella Supertone horns. AutoZone
probably has them. They will bolt right on to your original brackets
and plug into your original wiring harness.