The large American cars of the 60s & 70s often had ample horns, although many junk yards aren't holding on to cars of that era anymore. Might be worth a look see.
Another vote for the Stebel air horn. Next to the big foot for the kickstand I got from Brent, the Stebel is my favorite little add on. It holds a tiny air compressor that winds up and makes for a mighty blow when the horn button is depressed. It's saved my bacon twice now when I was in the blind spot on a multi-laned highway. I wonder if I'd still be here with the factory "meep-meep." My only complaint is it could be a bit more discordant, to make for that head throbbing instance when a tone is off by around 3/4s of a step and the two sound waves battle each other, but all in all, it gets the job done.
As a born and bred hard core Swamp Yankee, (who to this day, still lives in a Yankee Swamp, 30 feet from my door) I pretty much save anything and everything, including old cardboard boxes. (These practices may well be as a result of too many Equine Encephalitis carrying mosquito bites - not sure.) I did not, however, save the factory horn. I introduced it to the waste stream, in hopes that it would never see the light of day again. It occurs to me now that the factory horn should have been executed under the toothed-claw of an ample backhoe, with video documentation of the same. Maybe someone can donate a stock horn for this purpose. We could send the video to Triumph as a "hint."
I think the Triumph engineer who tuned the stock pipes spec'd the stock horn as well - Edward J. Shooshington - E. J. for short.
