HKS 2530 on RB20DET with 1.2bar made 230rwkw in mates car - this is with FMIC, full exhaust and increased fuel pressure, pod and EBC. Stock ECU (not chipped), manifold, plenum, afm. He also runs a catch can and oil cooler. This car has heaps of midrange, which it needs as its a drift car. He has driven this car hard for a couple of years and never had a problem with the internals. If you have a copy of the latest HPI mag, his car is featured in there - its the cefiro. Remember if you want a streeter, a car with good midrange will beat a car with top end power every time - but if its for drag, different story (depending exactly when it comes on boost).
I would imagine that a HKS 2835 would put you up around the 250-260rwkw mark. If you use a small turbine housing and large wastegate, it will bring it on boost earlier, making it more streetable - but you may find the injectors are starting to thin a bit, and the fuel pump may well need an upgrade. this also means ECU will need doing - its really going to add up. The HKS2835PRO has a t3 turbine inlet, and will bolt straight up, which would be a bit cheaper if you wanted to retain the stock manifold - but still need to do injectors, fuel pump and ecu. Also with the PRO you can keep the same dump you have now.