Yea I dont understand jetting at allremember that temperature and elevation are a huge factor in jetting.
The concept is fairly simple. Higher temperatures makes the air less dense (less air in a given volume than with cooler temps). Higher altitude also makes the air less dense (due to the lower atmospheric pressure at higher altitudes). So the hotter and/or closer to sea level requires a larger jet (more fuel) to keep the air/fuel ratio at an optimal mixture. Run the mixture too lean (too small of a jet) you run the risk of burning pistons or valves from a hotter combustion. Run the mixture too rich you run the risk of fouling a plug. Richer is safer than lean, but lean makes more power.
If I remember correctly, the jetting is the same from 0 to 3000 ft. One jet size less for over that. It is in the jet kit instructions though. I would think you could find something that works all around. Just check your plug from time to time to see if it is rich or lean. White plug electrode means lean, black means rich. A little lighter than chocolate is good. Do a search on the web there are some pictures of the different conditions out there.