Abstract: A catalytic converter includes a shell defining first and second shell portions. A first substrate supports a reducing catalyst in the first shell portion. A second substrate supports an oxidizing catalyst in the second shell portion. The shell further includes inlet and outlet passageways. The inlet passageway is disposed in the shell adjacent the first shell portion and allows combustion products to enter the shell. The outlet passageway is disposed adjacent the second shell portion and allows combustion products to exit from the shell. A third passageway located longitudinally between the first and second shell portion allows combustion product to flow readily from the first shell portion into the second shell portion. A manifold introduces air into the combustion product flowing through the third passageway and an air fitting provides access to the manifold through an exterior wall of the shell.