Silencer goosed

Hi all,
My rear box has finally gone, it's the original one, so has lasted well I reckon. Would welcome any input from folk who have done exhaust replacements. I did fit a 3/4 Double S stainless system to my old Disco 300 TDi, it was excelent, but only a silencer seems to be available from them for my TD4 Auto, 02 reg. I believe I am not able to junk the cat, as the car is post 2001. I would love to junk the centre silencer and fit a closer fitting stainless system if possible, probably from the cat down I guess.
The original silencer is blowing a bit, but not bad enough to upset plod, but it wouldnt pass an MOT.
In addition, what are the signs of a cat on its way out? My exhaust does smell a bit sulphurous at tick over, even when hot.
Fuel consumption and engine performance is spot on!
Am almost minded to fit a Bosall replacement silencer, as I can get one cheap, they are OEM on some older DAF trucks, but are their aftermarket "car" ones long(ish) lived?
BTW just had to fit a replacement silencer to a 2year old DAF 105XF.....£4200!!!!!!!(not Bosall).
Thanks

Bosal boxes are normally very good and as you say they are an OE quality manufacturer.

I specifically sourced a Bosal tail-box for my 90, it was identical to the genuine box it replaced and lasted just as well as the original system (which is always a good indicator).

Did this to mine new bit of bent pipe and a powerflow rear box ,
The lump to the right is the LPG tank it sits where the original back box was but I'm sure you could do the same sort of thing on a oil burner.

Thanks Edge, looks interesting. Noticed my mates ancient D1 "H" reg has a tiny silencer poking out behind the rear n/s mudflap. Doesnt seem to be over restrictive and it's quiet.
Plenty of choice in slim aftermarket so called universal silencers, so may go this route. With bikes silencers need to be approved with a stamp and BS number, on bikes 2001 or younger, are cars similar or can I legally fit anything I fancy as long as it is not "offensively noisy"? I dont want a noisy system anyway, lol

Bought a box today Bosal only £45 and easy to fit.

There is No catalytic converter test for diesel engined vehicles (any year)

As far as I know just by a pipe and stick it on but the Power Flow I used it a bit noisy
and sounds like a boy racer corsa on full chat.
A universal baffel from a bike retail outlet sorted it out and restored a bit of the midrange
that is lost due to the freeflowing exhaust.