For my own curiosity and to see if it was possible for future mods, I ordered a 4 Bar map from Europe a few weeks back and it just came in yesterday. I unplugged the 3 bar and plugged in the 4 bar just sitting on top of the engine and it read 490 mbar of ambient pressure, which is way off. It should be around 800 mbar here at 6500' which is exactly what the 3 Bar read.
So I went in and adjusted the MAP calibration in the tune to fit the new curve for the 4 Bar. Instead of having a range of .4V(200 mbar) to 4.65V(3000 mbar) like the stock/GM 3 bar Maps, the 4 bar operates from .5V(500 mbar)-4.5V(4000 mbar). After doing this and uploading the tune, I was getting the appropriate 800 mbar. With the Jeep running in Park it was sitting at 840 mbar, same as the 3 bar map. I have driven it around yesterday and this morning and all seems perfectly normal.
