If the boost gauge is a 11:00 o'clock you still have some vacuum in the intake manifold. Although not much. The light grey smoke is usually an indication of oil be burned. Has your oil consumption increased? Maybe check for excess oil in the intercooler. There's a drain plug in the bottom on the driver's side. Should drain out only a couple spoonfulls. Check your compression also. Your car is in the mileage area when the turbo cylinderhead gasket sometimes start to leak.