You should be fine, go have a read of the HG thread along with a squizz at the RB25 dyno section etc....
My car was running 200kw when i got it with high flow turbo, Power FC, Standard AFM, Standard Injectors etc.... I upgraded the injectors to 550cc and ran 250kw still running the standard AFM (However i would suggest you upgrade it if you are going for a retune anyway), make sure your fuel pump is up to the task and ideally have exhaust, cooler and some form of boost control.... There are many ways around making power but simple ways are very effective!