"The VATN is a whole new deal. The vanes of the VATN pivot to present varying ares to the discharge stream, changing the exhaust gas velocity as it enters the turbine, permitting the speed of the turbine to vary. The merit of the VATN lies in several areas: it acts like a small A/R when asked to do so, a large A/R when required, and it produces a smooth transition through all points between the two extremes. The VATN can create such a huge A/R that turbine speed over the entire range of operation can be controlled by varying the A/R alone. Thus, the VATN becomes its own boost controller, and no wastegate is required. When no wastegate is present, all exhaust gas energy is available to power the compressor, and "waste" becomes a thing of the past. Turbine performance can take on whole new dimensions. Since turbine speed is always controlled by the VATNs, the A/R ratio is always the largest possible for the boost pressure at that instant. If the A/R were smaller, turbine speed would rise, creating more boost, which would raise the turbine speed, which would raise boost again. This situation will always keep exhaust gas back pressure at its lowest for any given boost pressure. This creates the wonderful condition of the exhaust back pressure being less than the boost pressure. When this "crossover" occurs, power production takes on new dimensions. This condition is generally not feasible with conventional turbos without the turbine's being so large that it becomes unresponsive at low speeds."