Hi, I'm new on here and thought someone might have an idea of whats wrong. When accelerating there is a kind of quiet shreiking noise (Not turbo whistle) which can really only be heard in the drivers seat, it started doing this about a year to 18 months ago occasionally. Now it is all the time, light or heavy foot. The car feels a bit flat lower in the rev range compared to a few years ago, and when floored there is a bit of a flat spot around 1800 rpm, then when you hit 2400 rpm it sounds like the boost is being dumped. I have changed the Air meter, the EGR solenoid, the boost solenoid, it had a new turbo and the oil feed bracket fitted last July, this has been happening since before the new turbo (new, not reconditioned). The car also runs a bit rich, tailpipes are a bit sooty, uses hardly any oil between services, never had to top it up, or even got close to needing it.