have you adjusted the actuator? im in the same situation just fitted a brand new K03s and i feels really slow going VW tomorrow have another MAF fitted see if that the problem and going R-tech on sat to see if my actuator needs adjusting!
had a new maf fitted and no joy but replaced my N75 valve and a little of the power is back can boost to 15psi but no happy think there is more issues regarding boost leaks and actuator issues!