It's a 02 GT 5spd, when the clutch is not engaged (out of gear just idling) there is a hissing sound and when the clutch is engaged it goes away....Throw out bearing?

Thanks guys, I beleive it is a T-45...(its not my car)

Anyone?

Yup T?O bearing. Sounds like an aftermarket clutch. My car has the same exact sound after I installed a Hays clutch and T/O bearing. If I am at idle and slowly let the clutch out then I can realy hear the hissing sound, as soon as the clutch is engaged the sound dissapears. I can make the hissing sound go away if I let all of the tnsion out of my firewall adjuster, but then the clutchshifts hardin gear or engage poorly.Sports cars never sound like normal cars, smell like normal cars, run like normal cars or are reliable like normal cars! There is always an annoying sound that accompanies these cars.