You are further away than I thought.
However, try this(near me in Wollongong NSW):
One set of Mitsubishi Lancer CG CH 2.0 litre 2002 to 2007 extractors. MORE POWER HEADERS. 1 5/8" primary pipes, 1 3/4" secondary pipes & a 2 1/4" outlet.
www.ebay.com.au
The non-turbo extractors as listed would be the starting point for getting a new exhaust system.
I don't know if the listed extractor suppliers are able to help you with the remainder of the exhaust, but contact them and ask.
Make sure you give them exact and accurate vehicle information.
Gladstone 4680 is a reasonable sized town.
I was last there about 8 years ago.
There will not be much trouble finding a local exhaust shop to advise about fitting the extractors and the rest of the system.
Just leave the intake system standard.
Modified air intakes do not do much, if anything.
Don't be misled into fitting an "oiled pod" or similar replacement intake.
Just leave it alone.
Standard, unmodified air filter elements generally flow just as well as any "aftermarket" filter.
Potential gains are minimal, at best, so just save your money.