I'm guessing you have a AVCR, has it been on the car before or have you just put it on. Mine did the same it would not boost more than 0.6Bar even when I set it higher. The problem was the front of the cat had collasped and wasn't flowing the air.
Definately go the Power FC, the real benefit of an SAFC is that it displays what the car is doing in regards to Air/Fuel/Throttle. The Power Fc handcontroller does the same. Forget SAFC.:talk2hand