I agree with others that traction issues need to be fixed (both the car and driver technique). My racing background is in disciplines where the steering wheel needs to be turned during the contest, not simply used as a hand hold for a few seconds.
Enough of the cheap shots from me. Upping traction and using what's available well can make up for power to a point. More power is of little use if the power that's available now goes up in smoke.
The compression in the motor looks like it could be a bit higher. Before I make a recommendation, I need to know what octane fuel is available down under (what you want to use more specifically)