The reduction of transport particulate matter emissions is crucial for improving air quality. Although particulate filters are efficient in removal of particulate matter, their inclusion in modern exhaust systems results in high back pressures and thus higher fuel consumption. Consequently, there is an ever-increasing demand within the automotive industry for more accurate and reliable filter design tools. A common modelling approach is to use 0-, 1- and 2-dimensional simplified filter flow models as part of the entire exhaust system. These models fail to capture the intrinsically 3-dimensional complex flow features present in the exhaust systems. In this work, a multi-channel modelling approach is implemented for the first time to provide full coupling within a CFD simulation framework. The strength of the new methodology is that it offers for the first time the ability to: (i) capture channel-to-channel flow interactions, (ii) account for density variations within individual channels, and (iii) investigate the overall effect of a given filter configuration on the exhaust system in 3D (i.e. upstream and downstream effects). The method retains the simplicity of a 1-dimensional filter channel model while providing an insight into the 3-dimensional non-uniform flow distribution between the channels. This approach represents an important new tool for exhaust system design and optimisation. Keywords: Particulate filters, GPF, DPF, Multi-channel, Pressure drop