I upgraded mine the other day to Phillips 85122, £59 for 2 from hids4u.co.uk - half the price of BMW, and a lot brighter too. The bluer a Xenon, the increase in colour temp. But also a decrease in output (lumens) - see below
4300k D2S Philips = 3200lm (lumens)
4300k D2R Philips = 2800lm (lumens)
4300k D2S Philips = 2400lm (lumens) actually 5800k
4300k D2R Philips = 2000lm (lumens) actually 5800k
4800k D4S/R (brand) = 3800 (lumens) ** brightest in the market
5800k D4S/R (brand) = 3300 (lumens)
7000k D2S other = 1790lm (lumens)
7000k D2R other = 1390lm (lumens)
8000k D2S other = 1180lm (lumens)
8000k D2R other = 780lm (lumens)