So many people have helped me in various forums so Id like to put a little back.

I had a Stebel on another bike but it was a bit of a challenge to fit it to my 2010 Ultra Classic. It is super loud and the best horn I have heard. I left the original on in the original position as it looks way better than the crappy 'chrome' they call on the Stebel..as its just silver plastic.. sucks..  I found a little better way than lots of the instructions I found online,

I know every bike is different but on the Ultra there is a great spot just behing the back cylinder and bolt it thru under the seat

Take the seat off and disconnet the positve off the battery , you can fit the relay under there as well

Run a wire from the positive terminal on the original horn ( splice it in or use a inline connecttion) run that up under the tank back to the relay. connect that to the #86 terminal.  

Use an inline fuse and connect a line from the positive on the battery and connect that to the realy at #30

Run an earth wire from a handy spot close to the relay and connect that to #85

BTW I would not actually fit the Stebel yet until you have all the wires connected as its hard to get to the terminal underneath it.

Run a wire from #87 on the relay to the positive on the Stebel . on the negative on the stebel connect a small wire up to  the same bolt that you are attaching the horn to and that will earth it. Bolt up the horn .. at a slight angle so it doesnt touch anything.. use a nylock nut if you can..

Voila!   when you sound your horn both horns will work.. if your getting the bike roadworthied or checked.. just take the fuse out of the inline connecter and just your standard horn will work. 

Scorpio great setup idea, running standard & stebal.  The stebal horns are unbelieviably intense, until I purchased one I had now idea what loud was.. I have them on all my vehicals & my bike. Trust me @ 139 dbs v 80 dbs shitheads hear you.