Cheap HID bulbs that say they're 4300K are often more in the range of 6000K. I've bought too many cheap ebay HID bulbs that state they're 4300K, but in reality only about 50% of them are, the rest are a higher kelvin rating. DDM tuning included. Also often times the two 4300K bulbs I get don't match in color.
The only place I know that sells consistently 4300K bulbs is TRS with their morimoto 3fives (haven't tried xb35's), but it's also a heck more pricey than most other bulbs.