all you're showing me there is whatever projector lense thats using is giving it the yellowish hue, or the phillips/chinese brand itself, because both of my sylvania 4300k HID's in non-projector housings are as absolute silvery white as you can get without a hint of yellow. Typically projector lenses make them look even more blue.... my gf's 5.0 with 4300k HID's with projector lenses has a slight bluer tinge than my 4300k non-projector HID's. My Stealth RT with projectors had 5000k HID's and they were much bluer than the 4300k. I absolutely loved the look so don't get me wrong there, but simply saying true OEM HID's of 4300k are not yellow. Possibly whatever brand or lenses you're using though give it that effect, but I've never seen it on OEM.
Here's a comparison shot for you side by side....
Philips 4300k vs OEM 4300k....I agree those phillips ones look yellowish, but the OEM ones look whiter to me!
Chinese 5000k vs OEM 4300k....I'd say thats about as dead nuts on of a match as you can get
Chinese 5000k vs McCullogh 5000k....I'd say the McCullogh 5000k are a lot bluer than those chinese ones.
(also on those comparisons, look at the projector itself, and not the housing around it as it skews the colors as well. Your housing is chrome, the 5.0 housing is satin, and the stealth housing is black, which all 3 reflect the colors differently. Just look at the projector lense itself)