Another vote for HIR's here, ran them in my last truck for lows and highs and loved them. I actually just replaced both of the lows on my Tahoe because one of them went out. I was surprised to find a white powdery buildup on the glass of both of the old bulbs. After putting the new bulbs in (which were clean, obviously), the output was noticeably brighter. I didn't replace them with anything fancy either, just generic run-of-the-mill Sylvania H11s from O'Reillys. Not sure how long the old bulbs were in there, but it must have been a good long time for them to dust up like that.
The low beams on these trucks are actually pretty well designed. Upgrade the high beams, and you could safely land small aircraft.