Ha, good luck with that... Scooter that comes with a good horn, Riiigght!
Try Piaggio, to put in a new horn I had to remove the topcase rack, tail lights, seat, all the rear tuperware, glove box and leg shield and finally the floor board. In their ultimate wisdom the horn is mounted under the floor board, and because of how the pannels are interconnected you have to remove all that first to get to the screws and clips holding in in. The only thing that did not have to come off was the front fender and front shield/headlight assembly.... Oh and I left the motor and storage bucket inplace...
But I do have an excellent Steble Air Horn now and an intimate knowledge of how she's put together...