My mate has just brought a 94wrx, seems to run fine but only boosts to 0.5 bar anyone got an idea why, got a full decat exhaust, induction kit etc?

Thanks - Matt

Boost control solenoid stuck closed ?
Mounted on drivers side front strut. Brass thing with 3 pipe, top, middle and very bottom.

This thing should start to tick as you bring the throttle off it's resting position.