Huh? I'm like a little over the 300hp/STI level (dyno proven) and I'm at Stage 2 (VF30, Injectors, fuel pump, etc).
Do a search on what VS0, VS1 and VS2 are (Vishnu Stage #).
Stage 0 is pulley, up-pipe, spark plugs, and MBC. Stage 1 adds an exhaust to it and Stage 2 adds VF30, STI injectors, Fuel Pump, EMI, etc. With your mods, you will probably want the Unichip at Stage 1 and YES, you will need some kind of boost controller (not your stock boost controller) for any of the stages.
With any turbo (stock or whatever), the more boost, the more power but tuning and supporting mods prevent your engine from going boom. Also, with the Unichip engine management system, you will need a boost controller (MBC or EBC).