Bell type horns on an Interstate

[DavRed]

I would like to mount a bell type air horn on my Interstate.
I have seen them on Tourers pointing towards the front. However not on an Interstate.
Currently I have BigBF quad horns, and the small air horns in each pod.
But I would like more of a Big Truck sound, rather than what I have..
Anyone mounted anything like that in an Interstate?
Ideas and pics, appreciated.

[DavRed]

The only ones I have found mount under the bike, and would require me to remove the BigBF horns. Not a good option in my mind...
Other Ideas?