they're not 1200, 1200 includes ballasts and bulbs. If you have stock Xenons you just swap your bulbs/ballasts.
Figure 600-700 for the clear housings, I've done this on e90's before
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Current: M2CS
Gone but not forgotten: Cayman GT4, M2C, 2011 135i, E83 X3 6MT, 2016 SO M3, 2012 335iS, 2010 135i and 2006 e90 325xi