you have a few options:
1. you replace the front end for the new style one, and even then there's no guarantees that it'll work because apparently you can only retrofit the LED xenons to certain cars and even then it's a complete pig to wire. to do this you'll need new wings, new front panel, new grille, bonnet and bumper as well as the headlights themselves. you'll also need new wing mirrors because for the facelift that's where the indicators are and they're not a straight swap. also the wings aren't a straight swap as the mounting points are different
2. you put LEDs into your exsisting headlight housings. i don't know if anyone has done this.
3. you buy aftermarket lights with LEDs in them, but they don't look OEM as the LEDs are in different places (they look like A5 lights). there's confusion as to whether they're for LHD or RHD cars and whether you can adjust the cone of light so you won't fail your MOT and they throw up all kinds of error messages.
in all you're opening a can of worms, and whilst i'm still seriously considering facelifting my front end (i have a 55-reg car) i'm not sure it's worth the expense. including paint you're looking at around £5k for the lights. are they really worth it?
