I just installed a bright *** light on my ultra. If you haven't seen one of these lights they are impressive. Very bright and noticeable. Pics are hard to capture the effect so here is a YouTube video. Piece of cake to install.
Kinda pricey relative to some other options aren't they?
Yes, but how much price can a rider invest in "safety." I say, if the $250 - $350 cost of a super-bright/flashy rear light saves one life...it's paid for many times over.
Highly, highly highly recommended!!! Brightest and highest quality taillight on the market. It is pricey. But you can't put a price on safety and getting the attention of tailing cagers. I keep mine on triple rapid flash then solid.