My car idle with a funny noise coming from the turbos. On boost, it doesn't make a nice spooling noise. It makes a harsh ratty noise when spinning. Boost is still strong, and blow off is not as loud. What happened? Bad turbo?

 

Are you sure its not the air pump? If so you will hear it between 3000-3500 rpm. Unplugg the electrical from the air pump and see if the noise goes away.
Dan