For those unhappy with the stock horn's performance (or the lack thereof) here's how I replaced the cheesy stock item with a pair of FIAMM Freeway Blaster 130dB electric horns. The installation is simple (takes about an hour or so) and the bike will look completely stock when done. I chose FIAMM's because I've had them on every bike I've ever owned, they're reliable, and they'll wake up the dead! [sm=devilgrin.gif]
I bought the horns from JC Whitney for $36 for a set of 2 (high & low tone.) High tone P/N is ZX133190A and the low tone is P/N ZX133191R. You may be able to find these same horns at a local auto parts store as well.
I bought a roll of 14ga stranded wire, a standard 15 amp fuse holder & fuse, some crimp-on male & female spade connectors, and a 12v, 30A relay (Part #275-226) from Radio Shack at a total cost of about $12.
Remove the stock horn & mount one Fiamm horn where the stock horn was. (No mods are necessary as the FIAMM mounts using the same bracket as the stock horn, & the chrome cowbell cover fits over the new horn so it still looks stock.) Leave the 2 stock horn wires disconnected for now.
The other horn you can mount anywhere. I mounted mine to a frame inboard of the right-hand saddlebag using an existing frame bolt (see pic.)
I mounted the 12v/30A relay in a cubbyhole just forward of the battery under the seat. (Your mount location may vary depending on what you prefer.)
All that's left is the wiring, which is simple (even for the electrically challenged, which I most certainly am) as the 4 terminals on the relay are numbered. Use crimp-on connectors as necessary. Using the diagram on the back of the relay package as a guide:
Using the 14ga wire you bought, lengthen and run the existing horn positive wire to terminal 86 on the relay.
Do the same for the existing horn negative wire & connect to terminal 85 on the relay. (These wires activate the relay when you push the horn button.)
Turn on the ignition and press the horn button- you should hear the relay click. If all is well turn off ignition. If not, double-check your connections.
Next, using the 14ga wire, run a 15A fuse-protected 12v hot wire from the + terminal of the battery to terminal 87 on the relay. (Leave fuse out till all wiring is finished.)
Then run two wires off relay terminal 30/51, connecting one of the wires to a terminal on each of the horns. (These are the hot wires to the horns.)
Each horn will have a terminal remaining. Using the 14ga wire, make a short jumper wire and connect one end to the remaining horn terminal on each horn & the other end to any ground. (I just used any available frame screw close to the horn.)
Tape all connections, then connect the fused hot wire, turn on the ignition, & the horns should blow when you push the stock horn button.
[My picture shows how I mounted & wired the rear horn. The wiring for the front horn under the cowbell is similar.]