Can you tune PSI based boost control without a 3bar MAP sensor?
 

I have a 2003 Evo that is setup for load based boost control. My friend has an Evo X and is willing to let me borrow his MAP sensor for logging boost. I ultimately want to do PSI based boost control. Is this possible to swap the MAP sensor from the Evo X to the Evo VIII and tune for PSI based boost control and when done, remove the MAP sensor and put the stock sensor back in?

No, because PSI-Based means it targets PSI, not load.

Remove the MAP sensor and the ECU has nothing to reference.

Thanks for the input Bryan...very much appreciated.