A burner for an exhaust gas treatment system includes a tubular inner housing having a closed upstream end, a reduced diameter portion, and a plurality of apertures downstream of the reduced diameter portion. An outer housing surrounds the inner housing comprising a bypass flow path therebetween. First and second tubular supports fix the upstream end of the inner housing to the outer housing and provide fluid communication between a cavity within the inner housing to a location outside of the outer housing. A plate fixes the downstream end of the inner housing to the outer housing and cooperates with the housings to partially define an aperture formed in a portion of the bypass flow path.