If it wasn't happening with the clutch pressed in while in neutral I's say throwout bearing. That makes it sound like something inside the tranny. Changing the gear oil may help, I'd try that first since it's cheap and can't hurt anything.
BTW, I have a whine in my tranny, mainly 3rd and 4th gear when not under load (light to no gas). It's gotten a little bit better with time (15k now) but it's still there.
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|RIP|6spd-sport|OSG-LSD|XP8|RBF600|Eibach Sways|RE-71R|FI-34Row|Gen3-CAI|Yaw P.S.|
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