Method of making converter housing size based upon substrate size

The present invention relates to producing catalytic converters. More particularly, the invention relates to producing catalytic converters, the housing or canister of which is sized according to a specified annulus between the canister and the substrate based upon a measured size of the substrate to be mounted in the canister. A catalytic converter is constructed by measuring a substrate to be placed within the outer shell or can, wrapping the substrate in a selected mat and loading the package (mat and substrate) into the can. The can is larger than it will be at completion of manufacture to render such loading easier. Subsequent to loading, the measurement of the substrate is used to direct the degree to which the can is reduced in outside dimension such that a selected annulus is created between the substrate and can, said annulus being occupied by said mat.