Detroit 14l turbo squealing noise

hello everyone.i got 09 western-star 4900 with series 60 14.0l motor.About month ago turbo went out on it.so i replaced the with new turbo and new dura-light CAC.while i was there i replaced all new gaskets,clamps,turbo pipe boots,bolts,nut etc..new intake gasket as well.about after 1500-2000 miles the turbo started making loud squealing/whistling noise.its more at low boost.once gets to highway speed it tend to quiet down bit.NO LOSS in power or mileage.getting 30-35 lbs boost..so i did the basic tests.sprayed everything with soppy water and didn't find any bubbles no where in the system.checked all bolts on intake and manifold side.everything seems tight.no soot on the exhaust manifold unless its under the heat shields. ill try to upload video of it soon.btw the egr/dpf system is non-functional (if you know what i mean)!!!
ANYBODY know what it could be??maybe bad turbo??

 

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Ill be making boost leak tester tomorrow.how many PSI should i apply to do the leak down test???

 

10-4!! Appreciate it.i Will try that tomorrow and get back to ya.also getting these codes .but no check engine light.

 

Ok so did the leak down test.didn’t discover any leaks.but closer inspection of the exhaust manifold did find small area with soot.also in tht area i felt hot air on my hand.