Interesting, I've heard of those PIAA leds, but never seen it in action. Let us know how you go with that. Just a quick note, I think the LED based bulb will draw a lot less power than the stock halogen ones, so you might get a "bulb out" warning if you switch them, because the computer may think because of the current draw, that the bulb has blown. Not sure what the cutoff point is though. Can be easily remedied with addition of a suitable resistor in the circuit, but you may not need to.
Someone else on the forum was playing with upgrades to LED bulbs, so his experiences might be helpful:
http://www.slkworld.com/general-modi...t-upgrade.html