I'm looking into this too. I ran a set of 6000k's on the mk4 and liked the look of those and the light output was very good compared with standard bulbs. They were a very white light with a hint of blue. Depends what you want from them really. From reading various posts on here about HIDs, 5000k seems to be where the most light output it. The further up the k's you go it tails off quite abit.