I ordered a brake light modulator for $6 from Flashing Module Instructions . Don't bother to waste your time. There are two issues with this unit.

1)It is designed to be inserted in line with your brake light, but the ground wires for it are not common (ie not passed thru). Apparently the flashing function is done by switching the ground line, not the hot line. This frankly is a silly design because it prevents the tail light from working at all.... there is no path to ground for the tail light when the brake is not activated. When I grounded the down stream side of the controller it allowed the tail light to come on, but the brake flash function was disabled. Silly silly silly.

2)I ended up wiring up some of Joe Florida's red LED pods as auxillary brake lights. The company sells two different flash rates 10hz and 20hz. The $6 module only comes in 20hz. In the daylight, the 20hz is visible as flashing, but at dusk yesterday when my night vision started, the 20hz was just too fast to see the flashing. From 20-30 feet back the brake looked like it was simply dim for a few seconds then went full bright. Not at all the effect I was shooting for. The flash rate of such a device should really be 2 to 4 hz... about the rate of a turn signal flasher with a burnt out bulb and no faster.

I've now ordered a flasher from a guy on ebay Motorcycle - Brake light modulator (4xfast, 4xslow, steady) - Up to 300 LEDs. | eBay that looks like it might do the trick.

The flasher from the ebay guy works great! Darned good use of $15.

Just what I have been looking for as well.

similar ground issues with the screaming banshee horn (highly recommended if you can deal with the extra weight) on the ZR7. The zr's horn is always hot and its the break in the hot that makes it turn on if that makes any sense at all.... anyway I had to order a second attachment from them to correct the issue. ps, that horn is sooooooooooo loud. Thinking about buying another one for the zed

Err ummm... I think you are saying that the horn is always hot and you complete the ground to make it turn sound??