when you say off the scale, do you mean it drops to load axis 20 on "map watch"?
if so, then yes you can rescale the load axis to move it around a bit
but remember a 3 bar map sensor is only 2 bar positive pressure
map sensors are listed as 3 bar or 2 bar or 4 bar etc but this includes 1 bar of vacuum or negative pressure (aka vacuum)
so if you have a 3 bar map sensor it will only read to 2bar boost