In automobile exhaust systems, catalytic converters have become essential to reduce environmental pollutions and contaminations. The goal of our research is to reduce the pressure loss and to improve the flow distribution under spatial constraint, simultaneously. In our past studies, we have proposed a flow deflector, which can reduce the pressure loss and improve the flow distribution in both steady flow and pulsating flow. So, in the present research, we try to estimate the more practical performance of the flow deflector, using the exhaust-gas flow from a gasolin engine.