Replaced the cat on my 2005 S Type Sport with new components. Would not risk used parts of this type. Yes, I accept the argument of cost of new parts BUT used parts could prove very expensive if you happen to buy a bad one. It is not just the cost of parts but also maybe having to do or pay for the work to be done twice. Also, running with defective cat can also cause other problems that can be costly.
My whole experience (and photos) are depicted in S-Type Section.
Best Wishes , John