Depends how much coin you've got.
From Herrod
* Cat back Stainless Exhaust: $1,483.50 fitted
* Hi Flow air filter: $100 fitted
* Custom tuned SCT Flash Device: $1,500
* Headers & hi flow cats: $1,180 fitted
* Cat back dual stainless exhaust: $1,800 fitted

Not cheap from them, but thats what you'd expect.

Hitech also do a catback system
http://www.hitechmufflers.com.au/produc ... ory&b=ford

Not sure what they sound like or who else makes them but its a start. The system will sound basically the same as a Falcon (surprise!) if they use the same mufflers.