An evacuator for supplying vacuum to a device in a boosted engine air system is disclosed. The evacuator defines a body comprising a converging motive section, a diverging discharge section, at least one suction port, and a Venturi gap located between an outlet end of the converging motive section and an inlet end of the diverging discharge section. A lineal distance is measured between the outlet end and the inlet end. The lineal distance is decreased in length if higher suction vacuum at a specific set of operating conditions is required and the lineal distances is increased in length if higher suction flow rate at the specific set of operating conditions is required.