Chips head work and the like may end up costing you the same as a good turbo setup. If you are serious about making the VCT go "a lot faster" then turbo is the way to go. The most you will get out of the AU motors is about 250kw N/A and that is a seriously worked motor with aftermarket ECU. think upwards of $5k.
For serious power I'd recommend turbo. A mate recently told me about this place Snort Performance Australia- Turbo Systems
who make bolt on kits including all bits necessary to turbo your I6 falcon starting at $3k for 250rwkw which is a hell of a lot of bang for your buck. They sell their kits on ebay too. I'm not affiliated with them in any way, I'm just passing on information incase anyone wants to have a go at me.
The best improvement for acceleration for your dollar is changing your diff ratio. Your VCT should have 3.45 so if you fit 3.9 or 4.11 gears you will see about 1sec improvement 0-100kmh for about $1k (IRS is more labour intensive)