Yes. But it is strongly recommended that you do not. Although it may not seem so, directing the light produced by a headlight bulb to the right places requires a good deal of precision. Reflector assemblies on cars that come equipped with halogen bulbs are made to direct the light produced by halogen bulbs correctly. Replacing those bulbs with hid bulbs that produce three times the light yields a terrible beam pattern. You will have light going all over the place, most importantly into the eyes of drivers of oncoming vehicles. Even if you can tolerate such a beam pattern, your lights would be a safety hazard on the road. Many people try to solve this problem by lowering their lights. However, to reduce glare to acceptable levels, you would have to lower HID lights in halogen reflectors so much that you would not have much of a useable light increase over your stock setup.

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