I have a mk3 8v. Get a magnex twin DTM back box and have a custom made powerflow pipe from cat to back box straight through in the largest bore stainless. Sounds a beaut and gives a massive performance increase for an exhaust system mod. If your anywhere near Redhill get Mark at RSR to do it. The man created a work of art under my car. Makes all the other Mk3 owners jealous at my local club. By far the best combo. I have now convinced 4 of my fellow dubbers to do the same. One of them ditched his expensive jetex system after he heard mine.
When i pull up at country pubs, people frequently ask if its me driving the TVR they just heard!!!
You can try doing a straight through (no cat) but this was just too loud when we tested it in the garage. Sports cat works great for me and keeps it nice and legal!