Hi,
A new member here with an R1200RT LC.
I wanted to fit some decent horns to my bike, but found it difficult (impossible?) to fit twin horns between the forks, even with Nippy Normans bracket. I have now purchased a pair of PIAA horns and fitted one to my own bracket, which is a piece of aluminium with two holes drilled, on the original horn location, where I fitted one horn. At this point I have to say my bike does NOT have the BMW radio fitted, so under the right hand fairing panel where the radio speaker would have been fitted, I found a nice neat place to fit the second horn. As the location is where the radio speaker would have been, it does not mask the horn too much. Again I used a small piece of ali to create a bracket for the horn. Wiring with a relay in the fairing near to the second horn and wiring back to the battery negative and positive terminals. Positive being the 'extra' positive rather than taking the battery out. Nice and loud!