Can the cat matrix in a re-packable silencer be replaced? This one is a Westfield one, but if one maker's one can its likely another can.

Although the ECU is producing lambda 1 the matrix is not working when connected to an gas anylyser, under full heat conditions.
I have spoken to Westfield parts, expecting to buy a replaceable matrix, but they don't sell such a part, or know if it can be changed.
Any knowledge or pointers appreciated.

Mal