I'm new to the whole lighting thing and I couldn't find a decent answer to my question after looking through 10 pages of search finds. The 02' WRX didn't come with an HID setup right? And the newer 04' and 05' WRX and STI can as an option? Can you use stock HID system from an 04' or 05' WRX/STI on an 02' WRX? Thanks for the help.

Afaik, the USDM my2004-2005 STi headlights (with HID) has a slightly different reflector design than the my2004-2005 non-STi impreza headlights. So I'm not even sure if a HID retrofit from my2004-2005 STi to the rest of the 2004-2005 impreza lineup is a good idea.

To make matters worse, the reflectors on on USDM my2002-2003 impreza headlights are designed for a different bulb than the my2004-2005s.

I don't think it is possible to do a plug-and-play swap of the HID unit into the my2002-2003.

If you retrofit it, it is likely that the beam pattern will be far from optimal. It may generate increased light output in the wrong orientation too.

Yep, it's technically illegal to retrofit HID bulbs with reflectors that aren't designed for them (i.e. stock USDM GDA ['02-'03 WRX] headlamps) since the light won't be properly projected.

Your best bet if you really want HIDs would be to get a set of JDM headlamps designed for use with HIDs. The only unfortunate part is that they cost over $1000...

If that's too much, you can get the JDM/Morette/Prodrive headlamps that use projector lenses with regular halogen bulbs which will collect and project more light than a reflector while using the same wattage bulb. Those can cost anywhere from $500-800.

If that's too much, you can get the JDM/Morette/Prodrive headlamps that use projector lenses with regular halogen bulbs which will collect and project more light than a reflector while using the same wattage bulb. Those can cost anywhere from $500-800.
The nice thing about the projector housing is that although they too may be halogen or HID bulb specific, the projector housings almost always have a panel inside that provides a good light cutoff to prevent glare. So, even if the beam pattern directed to the road may not (~although it may~) be as good as a factory-designed HID headlight, it won't blind oncoming traffic the way a HID bulb is retrofitted to a reflector unit designed for halogen bulbs.

Originally posted by satrya
The nice thing about the projector housing is that although they too may be halogen or HID bulb specific, the projector housings almost always have a panel inside that provides a good light cutoff to prevent glare. So, even if the beam pattern directed to the road may not (~although it may~) be as good as a factory-designed HID headlight, it won't blind oncoming traffic the way a HID bulb is retrofitted to a reflector unit designed for halogen bulbs.

Very true. Someone on SCIC had a great picture of a HID retrofit to JDM non-HID projectors. :) Beautiful light cutoff and still bright as can be.