Mine does the same thing, the only thing I could do to stop the noise is rest my foot on it a little, but my flowmasters are broke in enough so where the noise isn't a problem unless I'm at a stop.

I have another problem with my clutch though.

Whenever I first start the car it makes a noise as if there is air coming out of the tires .. I know it's clutch related because when I press in the clutch pedal the noise stops or gets interupted. It just makes a pssssssssssssssssh noise on and off until the car warms up.

wtf is that?