I did the main beam
with the new Touratech unit. Replaces the whole thing so you get a different beam pattern as well as the benefits of HID illumination.
Fitting takes about 2 hours, nothing technically difficult, just a couple of fiddly bits fitting the ballast bracket. This goes up in the frame behind the steering head, at first you think there's no way, but once you've sussed it it's neat and discreet. No drilling, cutting, modifying required.
If your bike has a 7.5 amp fuse this will blow as the unit powers up - happened on my mates 2003 bike when I fitted his. Didn't happen on my 2000 model, no idea what fuse I've got - it must be an inline jobbie as it's not in the fuse box under the seat. Anyway if you swap this for a 10 amp everything runs fine. Interestingly BWM don't seem to know what's right either, 2 identical Adventures in showroon, side by side, one with 7.5amp and the other with 10amp - go figure.
Highly recommended for greatly improved light spread and range over original main beam. Definitely value for money (£260 ish)