New regulations and standards for noise emission increasingly compel the automotive improvements about decreasing the engine noise. Considering the cost and the volume of the muffler in the vehicle, the aim is to develop smaller and more compact designs without any loss from the back pressure in muffler. Proposed ne should be analyzed with respect to both acoustics and back pressure. In this study, a reactive perforated muffler is investigated. The present muffler was analyzed to obtain acoustic characteristic. The back pressure affects the engine performance directly an acoustic and flow analysis of the present muffler was examined and compared with experimental results. Transmission loss values obtained from numerical analysis have shown a good agreement with the experimental results. Back pressure values from numerical analysis were calculated with a 20% margin of error. The results of this study will be used as a reference to be able to design new mufflers. So, prior to prototype manufacturing, which is a long and expensive process, different muffler design numerically by examining the effects on acoustic and flow characteristic of the muffler of each parameter, alternative muffler designs will be generated.