Over the weekend I rigged up my Sirus radio to the bike, and today I installed a Fiamm Freeway Blaster horn that I picked up at Pep Boys when I was out shopping for a dual port 12v adapter. I wired the horn in with a relay running from the battery with an inline fuse, tapped into the original OEM horn wires, and mounted it on the OEM bracket. The horn bracket has a large hole with a slot when you remove the rubber grommet, so I was able to manuever it around to make sure it cleared the radiator when I turned the bars, and that it was far back enough that (I don't think) full fork compression will let it hit the fender.
I also took an old helmet visor and made a visor for my gauges. I used 2 pieces of double sided tape, one on the visor and one on the top of the gauges and then stuck the tape together, because I couldn't get just one piece to stick. I might end up going with velcro if it doesn't hold good enough.
Couple pics:
Sirius setup- basically, zip tied the car kit onto the top of the brake reservoir, ran the antenna line down along the handlebars and mounted it on the clutch reservoir. Line out runs into a battery powered booster amp in my tank bag, and ear buds plug into that. It works great. A little vibration but that's because the car kit has a suction cup on the bottom. I'm going to investigate modifying the car kit and come up with a better mount but this will work for now.
The dual port 12v adapter I got. The end that plugs into the bike pivots.
Fiamm horn