The work has demonstrated how the conceptual design process can be improved by allowing the seamless and automated sharing of geometry information between a commercial CAD system and a commercial one-dimensional Computational Fluid Dynamics code for the purpose of fluid dynamics analysis of exhaust systems. The driver for this work was the need to carry out conceptual aero-acoustic design of an exhaust system where the simulation model included the intake, engine, and exhaust system. The exhaust system is modeled in the fluid dynamics domain using parameterized building blocks. The integration achieved via the pre-processor developed makes it possible to associate these building blocks with the solid geometry defined in the CAD system and to use this connection to determine their geometric parameters.