G'day,
As Ash mentioned, I'm currently going down this path now as far as tuning goes.
As far as mechanical/suspension work, I'm getting all that done at Techsport as I've never heard anything but praise for their quality of work. They're very reasonably priced too.
The ECU side of it is a bit more tricky. If you're happy to pay $$$ to get an Autronic or MoTeC, then you'll find that MPC will do a good job.
There are a few products (such as ECUFlash) which have the ability to reflash the factory ECU, unfortunately, there are no shops here in Melbourne (other than AVO) that I've come across which have played with it. Give it time though, as it's very quickly gaining popularity in the EVO community. I've been speaking with MPC about ECUFlash, but as of yet, haven't been down there to show them the software and what it's capable of.
When you're ready to get your car tuned, drop me a PM, and I'll let you know where I'm at re: places to get tuned.
Cheers,
matt