whats makes oem hids so much brighter than pnp kits?

 

Depends on what type of bulbs you use. 4300k bulbs are the brightest bulbs you can buy. The higher the number, the more blue/purple the bulbs will be and dimmer the light output will be

 

He asked about OEM HID vs. PnP. You can get PnP kits in 4300K.

OEM HID projectors are specifically designed to put the light where you need it, with a nice, even, widespread beam pattern.

A PnP kit in halogen projectors, on the other hand, will have a narrow beam pattern, and will generally put way too much light where you don't need it, like directly in front of the car instead of farther down the road. With halogen reflector headlights, it's even worse because there will be major glare in all directions, in addition to the hotspots all over the place.

And if you do go with the higher color temperature, it starts to be about the same as high-wattage ricer headlight bulbs in terms of brightness, glare, etc.

Hopefully these pics will help convince you:

My car with an HID kit consisting of Philips components, including rebased Philips 4300K bulbs in my stock Integra halogen projectors:


And here's my car shortly after completing my HID projector retrofit using Hella bi-xenon projectors from a Mercedes E-class:

 

The proper term is Optics.... The reason oem hid reflectors or projectors seem brighter than pnp in either is simply because the oem housings are designed around the HID arc and output.

Also the shape of the light and output of both looks differently, HID looks like a bright glowing worm (as seen thru a welding mask), it's uniform in it's brightness from start to finish. Halogen is brightest in the middle and get dimmer as it goes to the mounting points, this comes into play because the light is not as strong and is in a smaller patch on the bulb.

Using the UDSM integra projectors as an example of how pnp kits suck is good but frankly the udsm integra's optics suck to begin with, most of the light output is coming from the bulb itself not from the light off the reflectors. It is possible to get good results from halogen projectors with hids (generally H7projectors work best per HIDplanet.com)...

 

yea, specifically H7 Valeo projectors used in Audi A4's and other European cars. I think I read on HID Planet that those projectors were sort of "adapted" to H7 use from HID projectors, which is probably why they take so well to HID capsules, needing only a simple adapter ring to make them fit.