Quietening a very loud performance exhaust

[BOH]

My Jaguar X308 XJR came to me fitted with a very loud and rather expensive stainless steel cat-back by Paramount Performance.

It's just too loud (my wife says she can hear me pull away from traffic lights about half a mile from our house) but given its cost and the standard Jaguar system sounds like a Toyota Pri*s, I've been wondering about modifying it.

Each branch coming from the shared centre box is fitted with two very narrow diameter silencers; would replacing one or both with a larger diameter one be a practical possibility - like this one from eBay?

http://www.ebay.co.uk/itm/UNIVERSAL-EXHAUST-SILENC...

[BOH]

I spoke to Paramount and they weren't overwhelmingly helpful.

I'm looking for a cheap solution as the car has descended into bangerdom and I'm skint!

Brother-in-law handy with a welder and will probably give it try and if it doesn't work, there are many second hand systems available.