I've got LED rear turn signals on my TBA, though not the type you're talking about. I have the license plate surround. Here's a pic. The center part flashes when you apply the brakes, while the outside part is the turn signals, which flash sequentially. [You may have seen this at Hansen Dam, but maybe someone else would be interested.]
The problem with them on my bike was that they draw less current than the regular signals do, so the system thinks a bulb is out and all the signals then flash very rapidly instead of normally.
The fix is a $10 (or less) part called a load equalizer, which balances things out. Don't ask me how it's installed; it was soldered in very neatly under the seat at South Bay Triumph, for a few bucks.
Philip
