Since I was a kid I always loved horns and sirens, and I wanted to be a truck driver so I can pull on that rope and make the trumpets screams, but I'm a informatic technician so yeah, but I still want to have a air horn in my car ahah.
I guess air horns are considered a warning device so, I daily drive two nuggets with beep beep horns, one of them (a Fiat 127) got a truck air horn (the cheap one from aliexpress) and it's pretty effective on the highway
But I really want to go the extra mile and put a SPDT latching button or rocker switch so I can switch between my air horn and my standard horn for MOT and city driving, but I don't really know how to do it, I just know that I need to take the 12V signal from the original harness but heh
Does someone already done that with train horn or truck horn ? I know these a pretty popular in the US, not quite in Europe unfortunately
If it's small enough, just take the two wires from your existing horn and wire it into your new horn. Check fuse sizes and current ratings, if its high enough you may need another relay.