@bivie - When you decide to turn that old truck into a new one, you won't have to worry too much about that. The fuel injection systems on new vehicles don't have that same problem. That's because when you go to a higher altitude into the thinner air, your vehicle's injection system will compensate for it -- for the most part.
The injector is designed to detect that situation with the thinner air, so you will be all right except for when you are at slower speeds. It won't spit and sputter, but it might not have quite as much giddy-up. It's nothing radical, and you may or may not notice it.