There's plenty of more or less similar aftermarket H4 HID replacement bulb+ballast kits. I went with something very similar to GSMarc's setup, but without the Touratech add-on.
I think my main beam is around 4500k. It lights things up quite well. Not a perfect beam distribution but it's a big improvement over stock. I find the H4 HID kits in the HP2 reflector tends to be a bit uneven, skewed towards focusing the light up high. So you have to adjust the height of the lamp quite carefully for it to be a good fit. Putting a passenger on the back throws most of the light onto oncoming traffic.
I strapped the ballast onto the left side of the fuel tank, just behind the radiator. That seems to cause no electrical problems.