Well, I have a exhaust, adjustable cam gears, and modded standard boost solenoid to run 14PSI - 233rwkw or 238rwkw depending on dyno, and now adding a power FC I'll let you know tonight.
If you want 300rwkw usually people go 2860s -9s and you will probably need new injectors / fuel pump to be safe. So in my opinion if your going to do turbos.. go big so your not disapointed with a little power gain for $$$$ (no point spending 5k+ for what ~40 kw)
My 2c.