Turbo Noise

[coyote23s]

Im having issues with my turbo. when my truck is warmed up pretty good and i give it some throttle and pushing boost i hear a high pitch whinning noise. i want to say that the noise sounds like metal on metal but not sure how to describe it. i pulled the intake off and inspected the turbo impeller for damage, rub marks and to see if it has any play in it. i found no problem. it only does it to me when i give it some pedal, i will stop when i let off of the gas, or some times it wiil stop when i give it more gas.

i have a F350 CREW CAB Long Wheel Base 4X4 with 150,000 miles. no mods, bone stock.

i am getting frustrated with it, any ideas would be great.

thanks zach