Spend the money on Front and Down pipes and a Hi Flow Cat so you get a full turbo back exhaust system.
That will open up the power a lot more.
You can still run a Power FC on a lightly modified car, as it will refine your Air / Fuel system to run at an optimum level.
Having said that, your car is stock besides a panel filter / cat back exhaust, 1 Bar boost and if your not willing to take on higher power levels, you won't really need the Power FC.
I would not bother with the 660cc injectors unless you are chasing big power figures.
Until you want a large amount of kW's, Power FC's / Injectors / Fuel Pump / Fuel Rail / Fuel Regulator / Z32 or Nismo AMF's / Boost Controller / Dyno Tune will have to come into play.
(1 thing after another)
Stock GTR parts like the Air Box + Filter / AFM's / Front Mount Intercooler / BOV / Fueling System are all good for 300 - 350 kW's.