Do some research on LED lighting, especially in the car. I have tried out several bulbs and found MANY of them cannot keep up. I haven't tried headlight bulbs specifically, but after seeing simple 3157 bulbs SPANK various LED versions, I highly doubt a headlight will be any different. In fact, I'd say LED headlight conversion, without spending a hefty price of getting some high end components, will be incredibly dangerous on the road.
Here's a pic of the orange 60-LED tower compared to the standard bulb. I had the hazards on and finally got a pic of it on the blink...
I have changed over many of my stock bulbs to LED, though. All interior lights are now LED. I found side marker/license plate LEDs that did go brighter than stock and are working great there. I tried the 3157 light on front marker and it definitely failed to keep bright enough. I did get the white 3157's as well and tried in the rear tail lights, but too dim (should have bought red ones). I ended up putting in the 3157 clear towers into the reverse of my Neon and it was a bit dimmer, but good enough.
I do, however, hope somebody can chime in and say "oh, this LED light easily beats a standard headlight", but I doubt the technology is quite there yet. I have no experience at all with headlight LEDs, personally. Only every single other light my car has available.
Good luck!