New Single Cats. for 6.0L V12

[Jaguar5993]

Hi,
I was just thinking ahead for my 1995 XJS 6L V12.
My Jaguar factory standard cats. are a little bashed and past their best(still all working ok)and I believe the lower, second cat. is not really needed in the UK.

Has anyone fitted one of those new, single cat. systems that are advertised on eBay from £175 to £214(per side)that comes with a 2 year guarantee?.
These are a lot cheaper than the Jaguar factory systems,(if you can still get them??).

These new systems should match my larger bore, that these 6L have and I am guessing that only being a single cat., it should be more free flowing??
I believe that the quality of cats. is all down to how much precious metal there is in them?

My worries are ;
Will it pass the UK MOT for emissions with confidence?
Can they match the original Jag 'Sports' cat. specification?
Will they last, as it only has a 2 year guarantee?

I would not be too keen to replace them in 2 or 3 years time.
Is it a case of 'You pay peanuts and you take your chance'??

Any thoughts?

UPDATE: Just found out that the single replacement cats. to have, is a 200 cell free flowing sports cat.
These cats can handle my 300+bhp and infact,can take up to 400+bhp.
They come in at between £250 to £400 each for a good quality one(cheaper ones on eBay).
So, as those new single cat systems are only £175+ complete ,I can assume that they are not sports cats........I guess, I have sort of answered my own original questions !!

Unless anyone knows any more about them??
Thanks.