Hey mate i remember you, i told you to see matty for tuning as you told me you had problems.
On matty's dyno i made 340rwhwp yet on the weekend the car made 420rwhp with the same set up except blown manifold gasket and has gone almost 121mph with 4psi less boost of what it was tuned on.
I would say it could be your mechanics have either done something to your car or matty isnt tuning it right.
As much as you are sick of spending money, your going to have to spend more as there arent many profesional skyline tuners/ builders here in qld
if you want pm your contact details and il give you a call
harun