Originally Posted by gcscott
When you need to replace a HID bulb, you should buy 2 bulbs at the same time and replace both of them. The reason is that the quality control (for the metal salts in the glass bulb) is not that great and when they purchase the HID bulbs for the install kits, all the bulbs come from the same lot and per what Kelvin they are.
So if you want to have your HID bulbs to be the same color, buy them in sets of 2. You don't want 1 old bulb at one shade of color and 1 new bulb another shade.
Agree 100%, true that, bulbs are not expensive, get the pair have a spare.