What decreases life of HID bulbs?
Most of us have played around with halogen bulbs and found out that the only thing that really decreases their life is over voltage and high G-forces. HID bulbs are more fragile, probably the number one reason is because the bulbs are running with non approval ballast. It does not matter how good the other part of the kit and bulbs are. If the ballast characteristics are not OK, the bulbs will die prematurely.