Amplified; there is a decent thread on Skylines Australia that you should check out.. It's 13 pages of people posting their RB25 dyno printouts and mod lists:
http://www.skylinesaustralia.com/for...howtopic=55845
Read through there, it will give you some idea as to what combinations work, and what kind of power to expect from those combinations. Remember, the real key to making any power with any motor is the tuning... You can bolt on thousands of dollars worth of bling and still be slower than a less-modified engine with a better tune. As said a couple times already in this thread you should look into a PowerFC or a similar stand alone asap, then focus on your turbo and injectors.
As far as maintenance goes, here's some items you should think about replacing: Timing belt, Timing belt tensioner, timing belt guide, oil pump, crank collar mod, water pump, head gasket, valve job with resurfaced head, all new gaskets, fresh exhaust mani studs, new thermostat, new clutch, lightweight or resurfaced flywheel, new spark plugs, replace any aging rubber hoses.