the monitor dosnt see boost at all it sees is an electrical signal which in map sensors case is between 0 and 5 volts 5 volts being full boost at sensor it does vary a bit sensor to sensor also resistance in car wiring can cause irratic readings but they are all tested in the same way and when they leave they are all the same but each installation is different and thats generally where anomilies occur .some cars it goes to 29. ## others it does not you are more than welcome to send it back and i will gladly check it on our tester and in a car to be doubly sure .