2.3 boost'n ok by guage but not performance

[buddmyster]

My 86 2.3 turbo is making a loud whirling sound when it boost's The gauge on the dash shows it boosting 10 n 12's so its all working ok but not delivering the boost to the motor. I'm running mostly on the 4cylinders. Sounds like a loud, high pitched hairdryer going off. Everything else is ok. This went out all at once so it sound like something went out. I would appreciate any help. Thanks Buddy. PS anyone have a preference which type and weight oil to use???

[Stinger]

I'm not sure I understand what you are saying. You're saying that somehow the boost is reading on the gauge (which reads intake manifold pressure) but it's not reaching the engine (which is disproved by the first statement)? What's "running mostly on the 4 cylinders" mean?