Is my turbo wearing down?..

[sepulchral]

In boost past 4,000rpms i hear a "CRSHHHT CRSSHHHHT noise that goes along with the spooling of the turbo. however the car boosts fine and driveability is not effected. I do notice the extinct smell of gas- more so than i did before the noises started happening this morning.

Please tell me what you think may be wrong!

thanks
MIKE