An apparatus sizes an exhaust component that includes an outer shell that surrounds first and second substrates. At least one sensor hole is formed in the outer shell at a location between the first and second substrates. A first end of the outer shell is surrounded with a plurality of first fingers to size the first end around the first substrate to a first cross-section. At least one first finger has a protruding portion at a first finger distal end that is longer than first finger distal ends of the other first fingers. A plurality of second fingers surrounds the second shell end to size the outer shell about the second substrate to a second cross-section. At least one second finger has a recess portion at a second finger distal end that receives the protruding portion of the at least one first finger.