An exhaust assembly includes an exhaust pipe, a first venturi member at the inlet end of the pipe and a second venturi member at the outlet end of the pipe. A diffuser/mixer is mounted at the outlet end of the exhaust pipe. A shield pipe surrounds a portion of the exhaust pipe. A shield member is mounted to the shield pipe and covers a portion of the first venturi member. The first and second venturi members operate to combine ambient air with exhaust gases.