So i did some reading on transmission noise and clearly our rx8's are noisy in about every aspect.. lol. But i really only came across other people saying they had noise when at a stop in neutrul. (mine too)

My rx8 is making a rattling noise right under and through 3k rpms when driving. its kind of lound and really doesnt sound sexy...

at a halt my rx8 has a nice rattle right under my gearbox, at a stop light my friend said he could feel the rattle with his left foot.
i can make the transmission noise go away when i engage the clutch. most of the time.
anyways.. help.
Thank you

 

I have the same issue, a few people suggested that it was the TO bearing, but mine is brand new so I'm not sure. I'd be interested to hear what others have to say about the issue

 

It does seem like a clutch throwout bearing gone bad. When you press the clutch it puts load on this bearing and could make the noise disappear...