I've had this question asked a few times over the past few weeks so it may be time to throw this in the sticky.
1 Bar Map(Manifold Air Pressure)=reads up to atmospheric pressure or ~105kpa, used for Naturally Aspirated Vehicles
2 Bar Map=reads 14.7psi+atmospheric pressure=~210kpa used for Forced induction vehicles up to 14.7psi of boost
3 Bar Map=reads 29.4psi+atmospheric pressure=~315kpa used for Forced induction vehicles up to 29.4psi of boost.
