Genuine 4 Bar MAP Sensor (Boost Pressure Sensor)
You will need a 4 Bar MAP sensor to run most turbo upgrades to their full potential.
A MAP sensor rated to 4 bar will read 3 bar boost. This is because the MAP sensor is rated to an absolute pressure which includes atmospheric pressure of approximately 1 bar.
You always want headroom when it comes to the sensor so the ECU can see over-boost and correct it should it occur!