I went with a Fiamm Freeway Blaster Low Tone on my 07SM on the factory bracket; the Fiamm cost under $12 OTD from the local Advance Auto. Not as badass as a Stebel (my 08 Genuine Rattler scooter has a Stebel), but waaay better than stock.
Interesting factiod: the stock japanese-made horn uses a 7/16" mounting nut, not metric. Go figure.
All that said, my primary horn is my right wrist...
