It's not your fault, mate. At the risk of sounding on-topic, your car is making the right horsepower for the mods you've got but there are two things you need to do to make it a much, much better/faster/more pleasant car to drive.
Step 1/ Sack your bleed boost controller and go buy a Turbosmart Eboost II
Step 2/ Sack your tuner. They may be competent but they're completely full of shit.
A quality EBC will bring the boost on early and keep it there.
A quality tuner will make sure your engine lives once you do the above.
Good luck, mate.