The OEM Mercedes MAP sensor is 1.5 BAR or 21.5psi. If you boost higher you will trigger the CEL. Not sure if anyone has put a 2 BAR(30psi) sensor in, or if the ECU can work with one. That being said, because of the size of the OEM supercharger, a 2 BAR sensor would be a waste without an upgraded supercharger(which nobody has done), or a turbocharger(been done once). The reasoning here is like the other guy said, a 185 pulley puts the supercharger in the red zone already so you don't want to spin the supercharger faster than that, so no use for the 2 BAR with a stock supercharger.

Horsepower does not come from boost pressure, it comes from AIRFLOW.