The use of computer calculation tools in order to reduce the cost of the development of optimized exhaust systems has turned out to be a generalized industrial practice. Therefore, considerable efforts are devoted to the development of suitable calculation tools, which are representative of the real phenomena taking place in the exhaust systems. In the present paper, the results of the application of a hybrid linear/nonlinear calculation method to the prediction of the exhaust noise radiated by I.C. engines are presented. First, a brief description of the method is given. Then, comparison is shown between the results of the calculation and experimental measurements, both for in-duct pressure and for noise radiated. The agreement obtained indicates that this method may be used as a design tool in the frame of the new methodologies presently arising in exhaust system development.