In this master thesis smaller volumes of a SCR catalytic converter should be analysed. They would be better for the system, because there is a shortage of space and better coats could show same results with a smaller volume. Another theme of the thesis is, if a catalytic converter, which should be backpressure optimized, makes really a lower pressure in the exhaust system. Up to now a 10 inch tall catalytic converter is used and is analysed in this thesis. Also 4, 6 and 8 inch tall catalytic converter are used for the experiments. In this analyses should be real conditions, although the experiments are made at a dynamic engine test station. The real driving cycle is fitted by a program that the engine test station is able to drive this cycle. Also there are analyses with stationary operating points, which experiment with slip and online proportioning. Slip means, that a SCR catalytic converter has more dosed ammonia, which exits unreacted the catalytic converter. The online proportioning begins with an empty catalytic converter, which is dosed with a defined mass. It should discover, if the catalytic converter can manage with defined ammonia mass or not. The real driving cycle contains a town, an open land and a highway phase. The proportioning is calculated by a control module, which is also used in a car. For the pressure experiments a full-load curve is applied. At the end of the test cycle the result is that a 10 inch tall catalytic converter is the best. The pressure experiment shows that a backpressure optimized catalytic converter really has a lower pressure than a normal catalytic converter.