Transmission noise in neutral
 

https://youtu.be/qS0TADtOJng

It goes away when clutch is pushed in or in gear.

Gets louder when revving

55k

Sounds normal to me. When the clutch is engaged and the transmission is in neutral, the input shaft spins and the sound is the gears spinning. As our cars lack sound insulation this is audible. Once you press on the clutch the input shaft stops spinning and the noise goes away.

Jason Cammisa raved about a similar sound in the 911R, again caused by lack of sound insulation (at 7:41) - https://youtu.be/HA4s2S0peZE?t=461

Normal.

Mine got worse when I added the white line trans bushing insert. Transmission noises.