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Preconverters and close-coupled main converters are viewed as key components in advanced emission systems to help the auto industry comply with tightened emission regulations in North America and Europe. Due to their close position to the exhaust manifold when compared to current main catalysts, the mechanical and thermal durability requirements on such close-coupled converters are significantly increased. A set of representative preconverter systems, with respect to back pressure and surface area, ceramic and metal substrate material was exposed to a 100 hour engine aging cycle, which is equivalent to approximately 80,000 kilometers under European driving conditions. This aging cycle is used by the German Autoconsortium (ZDAKW). In order to address the high thermal load in a close-coupled position, the preconverter inlet gas temperature has been elevated to a maximum of 950 °C at stoichiometry. Maximum preconverter midbed temperature has been found close to 1000 °C.