True HID bulbs come in D2S (for projector light setups) and D2R (for reflector light setups) types. In order to get an HID setup for your EDMs, you'll have to get an adapter ring to change the bulb from D2S to H1. Or you can just buy an HID kit with D2S bulbs and modify your projector unit so that it will house the bulb properly. Instructions on how to do this can be found on the HID forums:
You will get optimal light output if you were to run an HID kit in projector units that's made for HIDs. Your current EDMs were made for halogen bulbs, and although going with an HID kit "should" be better light output (although it may produce glare due to the optics) than going with a halogen bulb, you will still not be at optimal level without projector units that were made for HID bulbs.