Exhaust temperature response is very important in the design of exhaust aftertreatment systems. Analysis of this response is made in this paper by means of heat transfer calculations at the exhaust system, leading to a model that predicts exhaust system and exhaust temperature response. Thus, the effect of differences in design of exhaust system components may be studied for optimization purposes. The model is readily extended to predict heating response of ceramic honeycomb filters. An approximate method for quick computation of exhaust system response based on the response of individual components, is also presented to facilitate the computations.