Originally Posted by sean_b
No I am not having problems with mine but I was hoping they would be brighter and whiter than the stock ones. I am afraid of heating issues with aftermarket bulbs.
If you need brighter HID bulbs then you want OSRAM XENARC SILVERSTAR; they are the brightest HID bulb on sale at the moment. Do not confuse brightness with whiteness; generally the whiter the light i.e. the higher the colour temperature, the less visible light you see. You don't want to go higher than 4300 kelvin if you value visibility over looks.
However, why do you need brighter HID bulbs, the standard oem Osram ones are plenty bright, they just need to be aimed slightly higher without blinding oncoming traffic. Also, you won't get issues with overheating as long as you stick to Philips or Osram bulbs of the right specification, which is Gas discharge/HID D1S. Car manufacturers use either of these brands, BMW uses Osram.