Dealer spec’d the Brad-Wht in the title.
What makes a WH “high altitude”?
I'm guessing here, but I'd say it probably has either a different gas jet or a larger air intake or both. You need more volume of air for the same amount of gas to get the proper fuel/air mixture or it will run lean and shorten the life. The gas is under pressure, but the air pressure is lower, and thus less dense than at sea level. Used to be you'd need to fix your car for that, but with the advent of fuel injection, that's rarely the case anymore.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013