It is...
Uprated fuel pump, STi VF35 turbo, Pink injectors, decent panel filter, maybe change exhaust, Class 7 plugs, good remap and you'll be near 320-330 bhp I would imagine with no probs...
Certainly turbo, and remap (a must IMO if changing turbo e.t.c.) and you'll be well on your way for prob less than £900
Everyone has there own way of doing things, and various routes...
I know before I went power, I made sure every bearing, bush, gasket and mechanicals were all replaced and uprated as after all the car is 14yrs old!
Build a solid foundation, and it will cope with the rest