I had it on my nightrain and wasn't happy with it. in my opinion it didn't make enough difference since all the lights changed the same and the brightness didn't change much. All stock bulbs.
I changed it out later for the Biketronics "Tailstopper" The turn signals stay off for running but light up when stopping. One light on for run, three for stop. Very obvious that I've got the brakes on when two extra lights come on. When I sold the Nightrain, I took it off and moved to the Road King. I'm very happy with it.