A selective catalytic reduction system may include a single housing defining a single centerline axis. The selective catalytic reduction system may also include a diesel particulate filter disposed within the single housing and having a DPF center axis aligned with the single centerline axis. The selective catalytic reduction system may also include an SCR catalyst disposed within the single housing and having a center axis aligned with the single centerline axis. In some implementations, the diesel particulate filter may include one or more SiC filters. In some implementations, the SCR catalyst may include one or more extruded SCR catalysts.