Do a search for the GCG Hiflow threads. Sydneykid has spend many hours replying in these particular threads as he has a GCG Hiflow setup on an R34 GTT pushing around 250-260rwkw (with a full listing of mods too).
My opinion is that replacing a turbo on an R33 GTS-t that only netts you 210-220rwkw is a complete waste of time and money. If you were to upgrade all the support systems (exhaust, fmic, fuel pump, ex cam gear, ebc, ecu, etc) then you would already be pushing very close to 190-200rwkw so how is 200rwkw -> 210-220rwkw worth $2k for an aftermarket turbo?
Different people want/expect different things. To me a turbo upgrade is a 40-60rwkw not 10-20rwkw.