The 'resonators' used on turbocharged Eclipses and Talons are a good idea, too. They come up to 3" and can be purchased from any of the DSM performance places (google on 'dsm exhaust performance', or start with these guys
Vendor Links or
DSM Tuners). If you don't see what you're looking for, give them a call and ask about buying just a resonator. The job if the resonator is to take the high frequency harmonics out of the pipe, thereby eliminating the annoying buzzing one can get without a cat/muffler combo.
PS - fspGTD has built a custom turbo-back exhaust for his Mk1 Rabbit TD, and has some great ideas. Using the search funtion enter his user name, then search back through his threads.