when I down shift to slow down like engine break, I hear a really wierd like chipmunk noise that gets louder the higher the rpms get. It sounds like a chimpunk yellng over and over again....I think I mite have a blown collector gasket on my 4-1...could that be the nose? it never makes the noise when excelllerating or low rpm down shifts.....i dont think it is the throw out bearing....any ideas...I know the sound game isnt exactly the best description.