Sorry my bad, I misread turbo back for cat back.
There are a bunch of ecu's available from the older powerfc's to Link, ViPec, Haltech and Adaptronic. It will come down to what your tuner likes using.
There are a few very good tuners with extensive experience with RB's that are mentioned regularly here at SAU. It might also pay to do more reading on who people like using.
DVSJEZ and Unigroup are two tuners I have no hesitation suggesting but there are plenty more in Sydney or thereabouts.