Thanks Barbbachello, I'm located in Norwest area of Sydney. Indeed the tuning shop is focused on Subarus and Mitsubishis, although these days they do a lot of other cars as well. The guys at Pulse Racing seem to know their stuff and Paul (the owner) especially has a Subaru background. They did give me the cheaper option of sticking with the standard engine parts, upgrading the turbo and with that they said this would max out at around 250kw at the wheels like you correctly said.
Maybe thats the smarter option, not sure. I think the 14k for the 6-speed gearbox was based on a full STI conversion with new parts.
Thanks again for your input, much appreciated.