I believe it should fit mate - send me some images (or post them here) of the fastener area and I`ll be better placed to tell you - is your bike ESA or non ESA?
Mark my bike is a 2010 twin cam GS, non esa, factory lowered version. Bike is 17 miles away locked up for winter, i will take some pics if you need em but it will be later in the week.
Geezer - don`t know why but I can`t PM ya - email me on [email protected] with your address and I`ll make you a bracket that fits onto the ESA bracket which you should be able to hang your horn on. If indeed it has the same fitting..............
Please let other tossers know that it fits as it may benefit others. Also feel free to express your opinions as its always good to do work for people on good recommendation and I am one for helping people!