yeah, I gonna leave this right here:
http://www.toyota-4runner.org/engin...-hids-everything-you-need-know-then-some.html
some notes:
LEDs: are generally directional meaning they need a special median to render them effective. Usually means some special projector. Otherwise you will have light where you don't want it aimed. However the aftermarket is getting TONS better. Look for vLed products.
HIDs: are multi-directional meaning they spread light freeking everywhere. This mean you should get projectors (they have cut offs so you don't blind the crap out of oncoming traffic). If you don't and throw HIDs onto your stock reflectors, then......................... yeah, please don't.