OK guys I'm gonna need some help again. Like the title says I get a hissing noise from the rear end of my car. It doesn't happen before 40mph but after that it depends on my rpms. At 3k its barely noticeable but by 5k it is extremely loud. It sounds like an air leak of some sort but idk what could be doing it. What else is really strange is when I was in the range of the noise(+40 mph) I tried pushing the clutch in and revving while cruising and the noise isn't there!? WTF could this be? Thanks for any help, I'm just trying to get an idea of what it could be. Oh and I can hear it clear as day even with all windows up.

 

Input shaft bearing? I'm just shooting in the dark. It matches some of your symptoms.
Clutch in and revving and the noise goes away.
Normal driving makes a hissing noise.

 

ISB is a possibity but that's not in the rear at all my vote is exhaust leak seeing as the revs would drop when you press the clutch in. 100% it's coming from the rear tho ?

 

100% its from the rear. And I would push the clutch in and rev it up pretty high and still no sound

 

Snakes on a teg?
http://tinyurl.com/obmxw8b