Have a look at my build thread -
Rossco's engine build thread That's how you get a
reliable 200+ Kw from an EJ20 (mine is about 232kw at the hubs in it's current form).
Admittedly I built mine stronger than I need to, but I built it to take a flogging and ask for more!
Currently it has very little lag (less than the stock Ej207 anyway) and is a punchy mofo in the midrange RPM's.
As the Pimp has said - 200kw from what you have isn't going to happen (easily or for very long) - Don't get hung up on numbers, they mean nothing. Set up the car's suspension and learn to drive it to the best of your ability - you'll be surprised how quick a relatively stock GC8 really is - especially in the twisty stuff.
Once you've mastered your car's handling (on decent suspension and a proper alignment) think about chasing better brakes and then finally add some more power.