http://www.ozmpsclub.com/forum/tech-...nty-fixes.html <-- first place to look for "issues" with the 6MPS
to ozmps
plenty of information in the forums, and im sure there will be plenty of people here to help you with your questions
in terms of mods, you're probably looking at ~130-140kw atw for a 6, with a Down Pipe, SRI/CAI and TMIC, around 170ish?
not sure about the rest of it...
but here is servicing costs:
Car Servicing Cost & Price Guide - carservice.com.au