Problems scaling PFC 4bar mapsensor

Having serious problems scaling a denso 4bar mapsensor.
How ever i do i always wind up like 0,2bars off the acctual reading and not
getting a good linear follow to the actual reading.

The original apexi boost sensor (3bars) has 6579 scale and 3289 offset

The new sensor i vould like to put in is checked that its linear and starts at
43kpa witch equals 0,17v and goes to 385kpa witch equals 4,78v

Have tried every thing i can think of but still no good results can some one
tell me how i should calculate the scale and or help me with this?

Need help urgently because the car is in the tuners shop now and all progres has being delayed because of this. We cant get it done!

Regards

 

PM cewrx7r1, he has a tuning notes package which includes a spreadsheet on calculating scale and offset for a MAP sensor