I have been using the radar screamer now for several months. There are pictures of my installation here if you want to see how it goes.
Full face helmet radar system.
Look at post number 9.
The great thing about it is that I have a loud exhaust, and I can always hear it, even if I keep it at low volume setting on the road at 90 mph. What it is is basically a car siren type of amplifier and it translates the beep from any detector into a high pitched chirp, which is audible just about anywhere. Here are the two things about it that suck - It is loud enough that others can hear it on the road, but this is no big deal because you can mute it with the switch. The other thing that sucks is that it cannot amplify voice signals, so you will only hear the beep, not he voice saying "k band," on a radar detector that has voice.