as said above i'd say its prob maxing out a little under 350bhp
i dont think adding anymore boost would give anymore power realy
as the exhaust housing on the turbo is going to be restricting it at that power
so more boost will prob just make the EGT's higher and not make much more power if any

go somewhere that knows what they're doing, if you want more power then,
bigger hotside for the turbo (.63 etc), ab07 cam and DECENT map, i bet its a differant car to drive