Noise reduction in vehicle exhaust systems is crucial for mitigating the adverse health effects of noise from roadside traffic. Improvements to engine exhaust systems could be one avenue to reduce vehicle and roadside noise. Therefore, understanding the insertion loss and transmission loss is of crucial importance as these constitute important metrics for the effectiveness of mufflers in exhaust systems. In addition, knowledge about the maximum emitted sound power is also desirable as it is an important characteristic of the exhaust system affecting the final emitted noise. This study provides an overview of the theoretical underpinnings of the acoustics that model engine exhaust systems, where the maximum sound powers are presented, as well as explores the sensitivity of the insertion and transmission loss to input variables. A sensitivity analysis of the transmission and insertion loss was conducted using data provided by Scania, a large Swedish truck manufacturer, from which it was concluded that the provided transfer matrix exhibit stable behavior. More generally, in face of specific perturbations, if some conditions are meet, the resulting change to the insertion and transmission loss may only be an upwards or downwards translation, or no change at all.