A refrigerant vapor compression system comprising: a first refrigerant heat rejection heat exchanger having a refrigerant inlet and a refrigerant outlet; a second refrigerant heat rejection heat exchanger having a refrigerant inlet and a refrigerant outlet; a refrigerant heat absorption heat exchanger and a primary expansion device operatively associated with the refrigerant heat absorption heat exchanger; a refrigerant line from the first refrigerant heat rejection heat exchanger to the refrigerant heat absorption heat exchanger; a refrigerant compression device having a first compression stage and a second compression stage; the first and second compression stages (30a, 30b) and the first and second refrigerant heat rejection heat exchangers (40, 80) selectively configurable in a first arrangement wherein the first and second compression stages (30a, 30b) operate in a series refrigerant flow relationship and the second refrigerant heat rejection heat exchanger functions as an intercooler for cooling refrigerant passing from the first compression stage to the second compression stage, and in a second arrangement wherein the first and second compression stages (30a, 30b) operate in a parallel refrigerant flow relationship and the second refrigerant heat rejection heat exchanger functions as a gas cooler for cooling refrigerant passing from the first compression stage characterized by further comprising an economizer circuit including an economizer flash tank, an economizer circuit expansion device and a refrigerant vapor line; the economizer flash tank being disposed in the refrigerant line downstream with respect to refrigerant flow of the first refrigerant heat rejection heat exchanger and upstream with respect to refrigerant flow of the refrigerant heat absorption heat exchanger; the economizer expansion device being disposed in refrigerant line upstream with respect to refrigerant flow of the economizer flash tank. the refrigerant vapor line establishing a refrigerant vapor flow path between an upper region of the economizer flash tank and the second compression stage. a first refrigerant heat rejection heat exchanger having a refrigerant inlet and a refrigerant outlet; a second refrigerant heat rejection heat exchanger having a refrigerant inlet and a refrigerant outlet; a refrigerant heat absorption heat exchanger and a primary expansion device operatively associated with the refrigerant heat absorption heat exchanger; a refrigerant line from the first refrigerant heat rejection heat exchanger to the refrigerant heat absorption heat exchanger; a refrigerant compression device having a first compression stage and a second compression stage; the first and second compression stages (30a, 30b) and the first and second refrigerant heat rejection heat exchangers (40, 80) selectively configurable in a first arrangement wherein the first and second compression stages (30a, 30b) operate in a series refrigerant flow relationship and the second refrigerant heat rejection heat exchanger functions as an intercooler for cooling refrigerant passing from the first compression stage to the second compression stage, and in a second arrangement wherein the first and second compression stages (30a, 30b) operate in a parallel refrigerant flow relationship and the second refrigerant heat rejection heat exchanger functions as a gas cooler for cooling refrigerant passing from the first compression stage characterized by further comprising an economizer circuit including an economizer flash tank, an economizer circuit expansion device and a refrigerant vapor line; the economizer flash tank being disposed in the refrigerant line downstream with respect to refrigerant flow of the first refrigerant heat rejection heat exchanger and upstream with respect to refrigerant flow of the refrigerant heat absorption heat exchanger; the economizer expansion device being disposed in refrigerant line upstream with respect to refrigerant flow of the economizer flash tank. the refrigerant vapor line establishing a refrigerant vapor flow path between an upper region of the economizer flash tank and the second compression stage.