To do it properly and to make the most of it, you'll need more mods....such as injectors, maybe a larger AFM - z32 and
as always an after market ecu is the best option. You can remap the r32 gtst ecu - but if your spending all that money on mods, you may as well make the most of them and get an ecu.
Why do you need a bigger turbo?
Whats the car going to be used for?
A basic upgrade would be an r33 gtst turbo bolted on.
Or even hi-flow your standard one.