Replaced mine with Osram CBI's. They are 5000k with the illumination of a 4300k. Best bulbs on the market hands down. A pure wight light without any loss in visibility. Had them in my previous M3 and had to get them for my 335. They are absolutely
Install is super easy though it will be easier removing the wheel first. The E90 section here has some DIY's. It is the exact same minus getting to the bulb. On the F30 you simply pop off the plastic fender cover in the liner to gain access. Everything else is the same from then on.