Look at it this way..
Summer is on the way.
AUS temps go pretty high in summer.
Just yesterday it was like 30 degrees and it's only going to get higher.
The standard cooler in winter is probably good to work efficiently at 12psi or less.
in summer, that standard cooler isn't going to do shit.
Get a good front mount and you will see an immediate improvement over the stock item.
If you have spent the money on getting a steel wheel on your turbo, then at the moment you won't be able to use that power until you change your standard pissy cooler.
You know the drill...
exhaust, filter, cooler, boost.
don't worry about water/metho injection or whatever...
do the basics first.
Keep an eye out on the forums for intercoolers that come up for sale.