Very cool, Ive been looking for a decent place to mount some horns for a while. I have some Hellas mounted to the firewall but felt like they reflect alot of the sound back at the cabin and was trying to figure something else out.
I kept the stock horn and wiring and used an add-a-circuit fuse off the horn fuse to feed a secondary relay'd horn circuit. This way I keep the stock horn intact and facing forward but if some shit head cuts the wire my hellas are still active. Plan was to have four Hella horns on the firewall this way but the reflection and sound deadening in that location has given me pause.
Hows the sound inside/outside, care to post up a clip??? I may give the electric airhorn a shot, that looks like a great spot.