An exhaust treatment device includes first and second substrates positioned in parallel within a housing. A baffle plate supports the substrates, an inlet tube and an outlet pipe, and defines a portion of a first chamber. First ends of the substrates and a second end of the inlet tube is in fluid communication with the first chamber. A partition supports the substrates, the inlet tube and the outlet pipe and defines a portion of a second chamber separate from first chamber. Second ends of the substrates and a second open end of the outlet pipe is in fluid communication with the second chamber. All of the exhaust flows in a first direction through the inlet tube, reverses direction through the substrates and reverses direction again to flow through the outlet pipe.