Its pretty unlikely it would be added even to the high end systems out there unless it came with it from the start. GPS signals are on their own satillite band. In order to put weather information it would seem to require another receiver that can pick up the radio band that the airplanes are using for their weather info, and might even have spotty reception on the ground depending on whether or not the signal is terrestrial or sattilite. So even with a fancy system, its not likely to be an "upgrade".