a friend of mine (more than 20 years ago) had an air horn mounted inside his front bumper in his Honda Civic (when bumpers were made of metal). His was loud. The only problem was it took maybe a 1/2 second for the compressor to spool up and make any noise come out of the horns. That was awhile ago and I've wanted to get one myself. Thanks for showing this and I too would be interested to see how yours works out and when you mount it. I would recommend mounting it as close to the front and pointed downward a bit (so water won't run into the horn.
I mounted electric/air horns under the hood of my '04 MCS. I sold the car and don't have pictures but we mounted the horns on the firewall on the RH side. We wired the horns by tapping into the OEM horn wire so that the horns operated with the OEM horn button. We tried to find room up front, behind the bumper, in the inner fender and the firewall was the only spot for fitment.
