clipper exhaust

Can anyone recommend a sports backbox that will fit an '89 clipper? I'm having trouble finding one as apparently the mk1 gti exhaust is different? I want it to have a deeper sound and a larger diameter tailpipe than standard to fill the bumper cut out more (maybe 3" - 3.5") but not sounding like a chavvy corsa or nova, just a deeper note!

I think you'd be happy with a Jetex system. They are nice systems, its looking like the route mine will be taking. You should be able to find one for about £200. This is a system from the downpipe back. It comes with a 3.5" tailpipe.
I've had jetex on my VR6 and more recently a cooper S, I used both daily and didn't find them obtrusive or chavvy!
The later cabrios were built on scirocco floor pans, hence why a mk1 system will not fit!