I found 2 loose bolts on my pressure plate but also another for the flywh pos sensor was loose and they never made any noise but the fingers were then working unevenly and this caused the release bearing to break off it's mounting clips and then strange clutch behavior began over 4000 RPM.
With the single-mass flywh there is gear rattling from the gearbox and can be heard from within the car only in a quiet environment while idling, or while standing at the back of the car. I'm not sure if that's what your hearing but it may be premature to tear out the tranny just yet. There's others who can add more than I can but let the scientific inquiry take its course Homeboy!
