Strange squealing noise after upping the boost

[Bradbain]

Hey guys just thought I would ask you what you think it is. Just recently upped the boost from 7.5 to 15 psi now it has a normal wistle then goes into a squeal, so i removed the boost controller put it back to standard boost and its still there, just quiter. Now when I bought the mav the guy said it had recently had a rebuilt turbo. Talked with the guys that rebuilt it, they said it could be exhaust gasket leaking but I am wondering whether there is a leak in the intake side somewhere.

[nissannewby]

Sounds like a boost leak. Check all your hoses between turbo and manifold.

Could also be your exhaust check all fasteners are tight and generally you will start to get a black soot build up where an exhaust leak is.

If these are good then a squealing turbo normally isn't good.

[Bradbain]

Agree with you nissannewby I don't think it's the turbo considering its been rebuilt

[Lieney]

As stated, it could well be a boost / exhaust / flange leak. Check all the hoses on the inlet side including all flanges etc for loose, cracked, damaged or oil residue around areas where air might escape.
If nothing is found with the inlet side, check exhaust side.
Point to note about a good turbo. I replaced my VVT in the ZD30 last year including rebuilding my OEM intercooler (which has lasted me about 9 months, but starting to leak again) and it tended to whistle quite audibly, when compared to the old one that $hat itself. I often have the passenger asking if I can hear a siren.