A system for treating exhaust gas from an engine is disclosed. The system may include a housing having an inlet port and an outlet port and defining a flow path therebetween. A fluid treatment element may be arranged in the flow path and configured to treat exhaust gas. A conduit may be fluidly connected with at least one of the housing ports and may have first and second tubular portions. The first portion may have a first cross-section with an inner diameter, and the second portion may have a generally elongated second cross-section with an inner width and an inner length. The inner length of the second cross-section of the conduit may be smaller than the inner diameter of the first cross-section of the conduit, and the inner width of the second cross-section of the conduit may be greater than the inner diameter of the first cross-section of the conduit.