I think your 9003 is what the search is for the standard headlights, reflector housings, but there are mach headlights on that car correct?The are H4 style bulbs, everything I've read says 9003 are what it uses. I can't find anything that suggests another type of bulb, but if I had the car, I would be able to check. I don't have it as of yet.
As of now they're an upgrade from halogen in terms of lumens, but they don't distribute light evenly to make full use of the lumens. It's like when you see HID retrofits in reflector housings, they just glare everywhere and not really put an light on the road. I don't know what an LED would look like in our (ancient) E46 projectors, but I don't think they would make full use of the light, especially if you have to rig them in. LEDs seem to make awesome off road light bars though.Why would LED be a downgrade from HID? They're far less fragile, there's no warm up time, they're just as bright, I don't see anything negative about it.