Turbo done for?

[talonite]

OK. so I have produced a new sound out of my car that is very un-appealing to me. Its almost like a scream, i thought for sure it was a boost leak, i still think it is, but i cannot find it. Did a boost leak test and the only thing that seems to be leaking is my MBC but it has a little vent on it and has always done it. My car drive just fine, everything seems normal but then i give it some gas and bring up the boost and it sounds like a small animal is lodged somewhere in my engine bay. boost seems to be holding at 14-15lbs. And i just feel like im chasing my tail here. Any suggestions would be apprciated. O by the way I have an evoIII 16g if that makes any difference.