My low beam HID (xenon light) died on my GTI :(, so, I read about it and found some nice articles:
1. Very detailed on fabrication and differences between real and counterfeit:
http://priuschat.com/threads/not-all-hid-bulbs-are-created-equal.101472/
2. Explains how to replace them in the GTI:
http://golfmkv.com/forums/showthread.php?t=14545&highlight=HID+Headlight
http://www.golfmkv.com/forums/showthread.php?t=158496
The key to success is to place the bulb first on the lamp. Do not try with the holder. No way you can align everything. First practice with the broken bulb. The bulb has the return wire, which goes on bottom (see groove in the lamp) and two notches, a square one (on top) and a round one (to the side). If you place the bulb in the lamp correctly, it'll stay there as long as you don't touch it/shake it. Then, carefully, you bring the plastic holder, with the contact in the bottom, a bit offset to the side. Notice that the holder has two grooves internally, at 180 degrees of each other. These match with the two pivots from the bulb. So, if everything is aligned, the holder will go in, all the way to the lamp, matching grooves with pivots and then you rotate it like 10 degrees and will do "click". Again, practice all this with the old bulb. It is easy and no strength required. The main trouble is the narrow spots to work with. Basically I couldn't avoid my bulb to touch the sides of the lamp as I was placing it, but seems ok...
3. Some people will recommend taking the headlight out:
http://www.youtube.com/watch?v=1ryUllFJoVg
4. On fake HID (HID-like) lights:
http://reviews.ebay.com/quot-Xenon-quot-and-quot-HID-quot-and-quot-Plasma-quot-bulbs-the-truth?ugid=10000000001832221
My car uses D2S. In Autozone I can get Sylvania (PN39223) for $100, 3200 lumens, 4k (temp/color).
but in xenondepot.com I can get a Philips (original OEM) for $70!! So, it's a no brainer:
http://www.kbcarstuff.com/Philips-4300k-D2S-Bulb-p/pb-d2s-4k.htm
Update (2/9/20): The link above is dead. So bought them from Amazon for $45 (nice, they've gone down...). Also I had forgotten to write down the reference of the Philips, so, just pulled my just burnt bulb (driver side) and it says: Philips Germany, D2S, 35W, 85122, E1, 03V, DOT 323A04
I didn't give a try to the ebay types, but may have worked out (not sure).
UPDATE (6/16/2013): My driver side (the other side from the above fix) died today... Just for the record...
UPDATE (2/05/2020): My driver side suddenly changed color to purplish. Still lights up but I am thinking that it may die anytime... We will see...
PS.: By the way, turning off the DRL (day running lights) seems to be only possible through Wagcom. Stupid :(
PS2.: More stupid even. Because DRLs are always on, the inner headlights are useless. Very nice write up here: http://www.golfmkv.com/forums/showthread.php?t=66060
