Have the P3's on my GS. The P3's run at a reduce level so they operate as a taillight and they actually waver or pulse a bit when viewed from the side. Web site says they do this so they stand out more when viewed at an angle, when viewed from straight on, they are steady. When you hit the brakes, they are very bright. Some mount them on both sides of their license plates, I made my own mounting plate and put them across the bottom of my plate, when placed end to end, that is about how big they are. This way I have two taillights that are easy to see and two big brake lights. And yes, my 07 GS burns both filaments in the taillight all the time at a reduced level that brightens when brakes come on.
I love my P3's, had a few of the LEDS go out in one bar. Contacted P3 about it and had a replacement in about two days. Only thing they asked was to have the bad one mailed back to them so they could see what went wrong. Mailed it back in the pre-paid envelope they sent. Great customer service.