Abstract: An improved exhaust stack for use with commercial vehicles such as semi-truck tractors. The improved exhaust stack includes an outer tubular portion that, if desired, can be chrome plated; an inner tubular portion that is coaxially aligned with the outer tubular portion and cooperates there with to define an annular shaped flow passageway; and a venturi tube section mounted within the upper extremity of the outer tubular portion, the venturi tube section being in communication with the inner tubular portion and with the annular shaped flow passageway.