I'm putting one on my wife's Yamaha V-Star right now. I did give it a cursory examination, and it looked like it would be an easy install (for the horn, at least) on my Storm. If her's sounds pretty good, I'll do the same to my Storm. It DOES require the install of an extra relay, as well as some wiring runs (which I hope I can do without removing the gas tank).
"It's like smearing butter into Keira Knightly!"