I don't think that HID is necessary on the K1600
I can't think of what you would really gain by the work! Traveling on I-75 last month, at night with an open area ahead, traveling at 80 MPH, the high beams lit up the road and I could easily stop in the area illuminated.
The K1600 puts out a lot of light and would not normally ride with the high beam on at night with lots of opposing traffic.
I needed a HID on my previous K1200LT because the stock light was not enough. Adding it made a tremendous difference, but I don't really see the need for it on the K1600.