If you've got all the skills of an automobile engineer then there's plenty of ways to do it - bigger turbo, modified boost map, revised camshafts, etc.
But for simplicity, a remap is about all you can do - there's a few good suppliers in Europe with substantial power/torque increases although I remain sceptical about their claims of improved fuel economy.
Put it in an i30?
Mines doing about 30k per set of tyres, how fast do you want to go?
Be a bit cautious of 'plug in tune boxes', that modify fuel rail pressure and boost pressure signals, I think it would be easy to over do it and hurt the engine. If possible look at the EGR system, I think great gains can be found there, my i30 ran much better, until the 'EGR Low Flow' code was set and the engine went into limp home mode.
Does anyone know of a company (in Australia) that can/will turn off the EGR system in the ECM? I believe there are two parameters that need adjusting, 'Minimum engine temp to enable EGR, and Minimum engine speed to enable EGR.