The factory MAP sensors on the 2003-2018 5.9L & 6.7L Cummins are a 50psiA (50PSI “absolute”) which means at sea level it’s natural reading would be 14.7psi of absolute pressure. The ECM then compares the reading of the barometric pressure sensor which should also read 14.7psi of absolute pressure at sea level to determine boost psiG. Thus 14.7PSIG MAP pressure minus 14.7PSIG BARO pressure equals zero boost pressure. This only allows the 50PSIA sensor to see a maximum of 35.3psi of boost (PSIG) at sea-level.
This sensor along with a tune adjustment allows the ECM to see and understand up to 130psiG of boost pressure, for you guys on the street you will now be able to see full boost pressure on your electronic monitors instead of seeing it stop at 35psi, for you competition guys you will now be able to see full boost pressure on data logs to be able to look back at and further dial your setup.