Mike6 mine is 2 litre too. Tried Cataclean, no joy, Cat was fecked.
Can’t source a new one anywhere (priced within reason) and few second hand ones no guarantee on mileage.
So a new exhaust was on the plans next year, so this has sort of forced my hand.
Hope it’s not your Cat! If it is let me know as I sourced 2 SH from reliable sources