A method and apparatus forms an exhaust component that includes first and second substrates. An outer shell surrounds the 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 fingers to size the first end around the first substrate to a first diameter. The plurality of fingers includes an extended finger that is longer than the other fingers such that the extended finger at least partially covers the sensor hole during sizing of the first end. A second end of the outer shell is then surrounded by the fingers to size the second end around the second substrate to a second diameter. The extended finger at least partially covers the sensor hole during sizing of the second end.