I would certainly be wanting to overtake the current HSV range if I was spending $10k on engine mods!
Cam, search around for all of these questions and answers as they are brought up regularly.
Threads like the upcoming fancy performance thread (
http://www.perth-wrx.com/vb/mechanicals/37762-new-fancy-performance-thread.html) will show you what mods, what power and what times cars have done in the past. Best way to mod, see what everyone else has done before you and copy the best suited bits to your driving style.