Just found a neat ccmbo horn and modulator. The banshee air horn is loud, the relay modulates your head light, and it also let,s you keep the stock horn in play for a friendly "beep beep" at the neighbor.
The required relay is optional. The horn can be wired normally. You can choose not to modulate the headlight and the air horn has selectable 1/4 or 1/2 second delay between the beep or the blast.
Going to own one as soon as I have a spare $100.