i had a boost problem where my car would only boost to 0.5bar, after everybody said it was the boost solenoid, actuator, dump valve, it turned out that the pipe from the t-piece to the inlet manifold was missing the 'restrictor pill' dont know how, dont know why but i have done a tempary 'pill' by using the tip of a biro.
it now boosts to around 1bar.
woooooooooooooooooooooooooooooo
cheers
rich

 

well done mate!

 

Top job Mate of mine used a golf tee, a little less brittle than a biro