Thanks, this is really useful! I have a radiator cover, so I will probably go with only one horn. Correction: I checked the cover and the screw seems pretty long, so I can probably put a second horn too.
This will be a project for next riding season. Another correction: I checked the prices so maybe I will get it soon. It's a close call between this, the Chain Monkey, a bottle of scotch or the new Call of Duty Cold War game.