As mentioned probably somewhere in this thread, the clips on the headlight assembly is one major reason for these prematurely burning out. Most of the time the clips are already bent beyond the ability to be fixed, if you bought the car used. If your tab is broken, the bulb isn't being secured to the housing and is vibrating, drastically shortening the life of the bulbs. When I had my HID PNP bulbs in the factory housings I used a piece of foam to keep the bulb more secure in the housing and had them for 4+ months with no problems.