Dave. I am on holidays and I just saw this post. Personally I think that the quality and size of the cats used by, or supplied to Morgan, are marginally fit for purpose. I also had absolutely negative results from trying to contact the manufacturer. I suspect that they are not interested in talking to end users.
It might be worth reading my post at
http://www.talkmorgan.com/ubbthreads.php/topics/432639/a-tale-of-3-catsAs you will see I replaced the original cat with a larger capacity and better quality cat. The car, some years later, recently passed an emissions test with no problems.