Catalytic converter housing

A catalytic converter includes a longitudinally disposed body portion having first and second shell halves and an interior through which the combustion product can flow. A manifold is provided for forming a passageway between the body interior containing a reducing catalyst and the body interior containing an oxidizing catalyst. The manifold includes first and second manifold halves, with each manifold half including a pair of flanges which extend perimetrally and substantially completely along the interior wall of one shell half. The manifold flanges are disposed substantially parallel to the interior wall and coupled thereto. The manifold flanges include a portion which is recessed inwardly from the interior wall and first and second mating sections. The recessed portions include air holes for introducing air into the passageway between the reducing catalyst and the oxidizing catalyst. The first mating section includes a stud and the second mating section includes an aperture sized and positioned to receive the stud of the first mating section. Each shell half also includes a portion of the interior wall for attaching the pair of manifold flanges to the interior wall of the shell. This portion has a greater longitudinal extent than the longitudinal extent of the pair of manifold flanges.