my r33 gts-t is having some problems in high revs. the car will build boost fine and seems to accelerate normal, but then at higher revs (5000-7000) a grinding / high pitched scraping sort of sound comes from the engine bay. i'm pretty sure its the turbo. when the noise comes in the car doesnt lose any power but it sounds really bad. anyone else had a similar problem? is my turbo about to die?