Yeah 5G is a nice amount to play with. Here's what you'd expect to pay here down under of decent stuff. In sort of an order i would do myself.

Headers - $1000ish
Jap Catback - $800ish
Intake manifold - $400ish
CAI Intake - $400ish
HD Clutch + Lightweight Fly + install - $1400ish
Cams + Springs + Install - $2000ish
ECU + Tune - $1500ish