Below are my install pics. On my '08 there was a nice place to mount the horn on the right side of the bike but for the cost of an extra M6 bolt.
Tools needed:
- Wire stripper. Not optional.
- Something to use to crimp wire ends on, which may or may not be the wire stripper itself, or a Vise Grips type wrench that can also be used when hooking up the high beam wire (see photo caption below).
- Anything needed to take off bodywork on one's bike.
- Extra zipties for wire routing.
- Multimeter, unless you can magically tell which horn and high beam wire is the positive one. I can't.
Time needed: took me a few hours, but I was lazing about in the sun in the driveway rather than working nonstop.
Anyway, the photos:

Weeny stock horn seen under the radiator. It stays in place with the Banshee setup, although one must muck about with its wiring, test which line is + and which is ground with a multimeter, etc.

New Banshee-branded airhorn, which is not a Stebel although resembles one closely.

Closeup of mounting bracket. Note grounding wire (for the horn itself) behind a few washers, which are there in turn to space out the back of the horn from the engine a few more millimeters.

Control unit ziptied in place, before any of its colored leads were routed laboriously through the bodywork (and ziptied down at intervals) to their respective destinations.

The red lead goes to the battery's positive terminal. Note that it's a crowded place: the other two positive hangers-on are for the battery tender harness and my heated gear. I had to fish out a longer M6 bolt from my toolbox to make it work. The control unit is grounded to the bike's frame, not to the negative battery terminal.

Orange lead goes to the positive terminal on the air horn. As above, the negative terminal on the air horn is grounded to the frame, not the battery.

Yellow lead is spliced into the positive lead for the high beam. I had to poke around with the multimeter to find which one this was, just as with the stock horn.

Once located, it still was a minor pain in the ass to get the yellow lead hooked up to the high beam positive wire. Cramped quarters! Pro tip: use a Vise Grips type wrench to shove the metal bridging/piercing connector down once all ducks are in a row, then close the plastic cover. You'll never be able to get enough leverage with the cover to shove the metal bridge through the wires otherwise.
The one thing I neglected to take a photo of is the lead going down to the stock horn. There one must figure out which lead is positive with the multimeter and then use the piggyback connector. (In other words, don't use the fancy piggyback connector for hooking up the air horn earlier! :lol: I did this but salvaged it rather than heading off to Radio Shack or busting out the soldering iron.)
I'll have a video demonstrating the sound and sights before and after installation as soon as the Banshee folks get me the correct part to get it all working right--yeah, it's not functional at the moment.
As it sits now I know everything's wired properly since when it actuates the high beam flashes and the air horn pulses. The problem is that it actuates as soon as I turn the key to the "on" position. (This is a known issue for pre-May production run units with certain motorcycles and they'll send out a free part to fix it.)