[Adger Smith]

Chad,
That is funny, but it is a little better than a SWAG.
There are formulas.
Have a chat with Patrick Hale.
A while back he had a discussion on the Comp Forum about what and how NHRA implemented their adjusted numbers. If memory doesn't fail me he even had figured out a better, more accurate formula.
Stockerstang,
In my early years I was associated with aviation. The aviation world has some pretty good ways of calculation power loss for altitude. Think what happens when you need full power to take off at an altitude airport. It takes a lot less power to fly in than to fly out.