If you're not far from Melbourne east, you're more than welcome to come have a listen to my RB25DET running mild steel 3" from the turbo back with a resonator and a twin tip Varex at the end. I supplied the Varex and the "cat", Performance Exhaust in Ringwood did the rest for $600. This was a good 5 years ago.
Couldn't be happier with the sound myself. It's not too loud (albeit illegally loud with Varex open), nice burble on idle, screams up top, doesn't drone at any rpm (even if it did the Varex is always there) and the Varex is still opening and closing brilliantly.