Okay, I had intended to provide some of you out there with something a bit more comprehensive, but my time is limited by studying.
What I have: Polarion 4100K H1 retrofit kit
Install was relatively simple but I still need to find a permanent location for my ballasts. There appears to be mounting locations on the underside of each headlamps (probably for OEM ballasts?). I apologize for not having a picture.
After about 2-3 weeks of driving, I've noticed a few things. These are ALOT brighter than halogen, but the beam pattern isn't as efficient as the Lexus', Acuras, Audis, and BMWs I frequently pass on the road. Also, those OEM HIDs appear to be a bit closer to blue whereas these are bright white. I thought I read somewhere that JDM is using 4700K? This may not be true though. I've also noticed the distinct difference in how OEM HID projectors (Audi, BMW) throw the light versus OEM HID reflectors (Acura, Lexus). Reflectors throw much more light, but cause much more glare. I can't tell exactly what Mercedes uses. Anyway, in the Mazda the HIDs make the cutoff across the entire beam pattern very apparent. It's pretty subtle with halogen because I never noticed it before. On very dark roads, it also lends to a slight loss of visibility beyond the reach of the beam pattern because of the high contrast. Not enough to handicap the driver, though.
Okay, on to some pics...
If you look at just the first two, you can see the hint of bluer white in the silverstars, but it's not much compared to HID.
The following pics were enhanced with brightness and contrast because the halogen pics were too dim. Pretty much, my camera was set with a pretty low white balance, but that reduced the issue of washout with the HID pic. In any event, I applied the same enhancements across the board, so these should provide an accurate comparison...
Notice the enhanced cutoff on the pine tree to the right of the beam pattern. Much more distinct with the HID.
Final verdict? I'm pretty happy with these headlights, though I'd like to see if 4300K is that much different. I feel like I'd be happier with something bluer, but in the end what is lacking is probably the OEM HID projectors (with the blueish-purple flicker at the cutoffs :) ) and not necessarily just color. I've been researching the possibility of hidtech.com or illusion-lighting.com for true DOT or ECE compliant HID projectors. I would need to see the improvement in beam pattern first, and haven't found any good pictures. Besides, it may not be cost feasible (for me) until sometime far in the future. I don't know what I would do with my current H1 rebased bulbs, either.
Here's a couple last pics...
Oh, and did I mention I like the blue to white color shift after initial turn-on? :D