I have their 4300K fog light kit, matches my LED angel eyes that are 6000K. I think the fiber optic in the angel eyes tones down the blue output a bit. Why did you buy 6000K? Do you have 6000K headlights? BMW uses 4300K HID bulbs, blue color is due to refraction of the light going through the projector lens.
Remember those science classes in high school with the prism? When light bends some of the color gets separated out. Same reason our sky is blue, the sunlight coming into the atmosphere bends causing the sky to appear blue.