raygun,
The dual (hi/low) Fiamm setups sounds very nice, as well as loud. The modulation of the 2 frequencies is unmistakable.
I had them on my 1988 R100RT and they were great - there was NO DOUBT that even cagers locked in their cars with the
windows rolled up, AC blasting, and 500W stereo bouncing their suspension that they couldn't still hear me if I held that button down.
The dual pitch horns make a nice "euro" kind of horn sound, like what you'd expect to hear on a Rolls Royce or something.
If your bike already has a relay on the horn circuit, it may be OK as is. But, my 82 R65LS (and I think most/all US models from 81-84 anyway)
did not come with a horn relay. Additionally, rather than grounding the horn through the horn button as many Japanese bikes did, these models
actually run the power wire for the horn THROUGH the switch, which can make matters a bit worse. The stock little round beep-beep horn on my
LS will only pull about 3 Amperes or so, which the stock setup can handle. Unless they have radically changed their design, many of the FIAMM
horns I am familiar with can draw up to 8 or 10 AMPS !!! This is more than what should be used with the horn switch and stock wiring on my bike.
You might get away without a relay with just (1) FIAMM horn, but it would be better to use a relay, and it is MUST HAVE if you go
with dual horns - part of the reason those horns are so loud / powerful is that they take alot of power ( electric current ) to
make that sound. The current for one horn is probably more than what your horn button switch should handle frequently, though it would
probably be OK if it wasn't used alot/frequently. Two horns is well over what the switch should be asked to handle, and the stock wiring
isn't that heavy either. As an engineer, I would recommend using a relay with one FIAMM horn for better longevity, but would strongly recommend
using a relay with dual FIAMMs.