An exhaust gas aftertreatment system includes a housing assembly and a reductant delivery system. The housing assembly includes an upstream housing, a first inlet tube, a second inlet tube, and a mixing housing. The first inlet tube is coupled to the upstream housing and configured to receive a first portion of exhaust gas from the upstream housing. The second inlet tube is coupled to the upstream housing and configured to receive a second portion of the exhaust gas from the upstream housing. The mixing housing is coupled to the first inlet tube and the second inlet tube. The mixing housing is configured to receive the first portion of the exhaust gas from the first inlet tube and receive the second portion of the exhaust gas from the second inlet tube. The mixing housing is separated from the upstream housing by the first inlet tube and the second inlet tube.