A new technique based on the insertion of a converging section in the driven tube is described which is capable of producing substantial increases in both reservoir pressure and enthalpy. A 1D inviscid full kinetics code is used to study a number of different locations and shapes for the converging driven tube section. For driven tube diameter reductions of factors of 2 and 3, the reservoir pressure is found to increase by factors of 2.1 and 3.2, respectively, and the enthalpy is found to simultaneously increase by factors of 1.5 and 2.1, respectively.