Well ditch that manual boost control and start using computers like all the hip folk.
Popular enhancement to any turbocharged engine is the installation of a Boost Controller, this little box will allow your ECU to fully control the boost at levels you desire (and capable of). Boost by gear supported on your ECU? Then you'll want one of these.
Our branded boost controller comes with the pigtail pre-made so all you need to do is connect it to your ECU and set your target boost.