This is what I came up with some time ago:
Sensor Output Voltage
The FSM gives the output characteristics with no scales marked on the axis. It does give some reference values however so I know various values between 760mmHg and 526mmHg. As the MPS output is linear it is easy to determine values for other pressures, I put these values into an Excel spreadsheet and then used Excel's 'Trendline' function to extend the line for output values between 0V and 5V, click here for details. Excel also gives me the formula to calculate pressure so I can calculate the pressure for any given voltage reading. The graph is in mm/Hg, when I get round to it I will to change this to show kPa which is the standard SI unit of pressure and the units that I will be using in the code. The conversion is quite simple, I just have to divide the value in kPa by 7.5.
MP Sensors usually don't swing fully rail to rail because of the type of output amplifier used so an output close to either rail is an indication of a fault.
From what I've seen MAP sensors are, for a given range, pretty much the same.
http://www.btinternet.com/~j_holland