There are some companies that make HID retrofit systems for the dual beams with lo/high together, but I don't think they're very popular or preferred as far as dependability goes. If you'd like to upgrade your headlights, perhaps go with a PIAA Extreme bulb and maybe some driving/fog lights. If you're set on HIDs, check out XenonDepot and email them to see what's available for your truck. I know they've done kits for the 3rd gen 4Runners, but don't know if they retained the Hi beam functionality or not.