I used Brisbane Exhaust Centre near the Gabba to get my resonater delete pipe fabricated on my Citroen DS3. Very nice service, reasonably cheap and FAST! The person I dealt with did everything, the actual sale, advice and the fabrication/installation. No damage to my vehicle. He took out the resonator and installed the pipe in approx. 30min.

They do custom exhausts there as well. I was going to get a custom exhaust, but the bigger expense didn't warrant the benefits. See if you can speak to Nathan (at least I think it was Nathan haha - if you go there he is the bigger guy who always wears a beanie).