ahh, the ecu wont be a hks 2540,odds are it would be a power fc if it was built in aus. first places i would look by the description you've written would be the inlet pipe from the filter to the turbo, in between the filter and theafm (might have something in there, ive seen wierder things), from there id go buy a cheapie bleed valve just to make sure your boost controller hasnt packed it in and from there id be looking at your manifold gaskets? let us know how you go with it