Constant whine / light metallic buzz sound

I'm trying to identify the source of this buzzing sound.
Setup:
-Gen2 gearbox rebuilt and fitted with a Quaife lsd. Fitted on my gen 1.
-Rey's cables.
-CS stage 2 rmm. Hardrace (OEM+, full rubber) side mounts.
It shifts perfectly, works well, no problem. Oil is fresh - Motorsport CRX LS 75w90 NT+.
(Before I had usual gen 1 gearbox, OEM cables, same CS stage 2 rmm, OEM side mounts, no buzz)

There's this constant light metalling buzzing sound (like a faint metal cutter/saw), higher the speed of the vehicle the more clear/distinguishable it gets. Doesn't matter if it's in gear or not, clutch depressed or not. It's different imo (higher pitch, constant) from the typical gearbox whine, which I'm used to and was present also with the old gearbox since changing the rmm.

The ONLY time it goes away almost completely is when I move the shifter right (left hand drive car - like going to change into 5th or 6th) and keep it there pressed but not engaging. Which I find odd and because of that I tend to dismiss other possibilities aside from transmission related, but in truth I have no idea.
(Later edit, after careful listening sound subsides when moving the shifter both right and left, although left it the attenuation is less)
Made some clips (attached) but it can be easy to miss, the buzz being a constant thing along the normal rolling sound:
Tried to catch it in neutral and every time the image shifts to the right I move the shifter (had phone in hand) and like 70% of the buzz goes away (muffled).
Any ideas would be much appreciated.
Many thanks

 

Hey man just wondering if you ever sorted this out or not? Just got done doing a new clutch kit install and all new components in clutch system besides the CMC…i have that noise on decel in gear when clutch is out, I have a single mass lightweight flywheel and all 3 stiff mounts so I expect some extra noise for sure but I’m wondering if it’s actually normal for this much...seems 50% of people say it is and they have noise and 50% of others that have the same clutch setup say they have no noises at all..the only thing i diddnt replace and diddnt learn about until after the car was just back together is that mazda made a revised release fork pivot ball also....i have a new release fork and wondering if its needing the new pivot also...i can feel that the fork has some vibration in it if you put your hand on it and goes right away once slave starts to extend...dont know if i could just need a tad more bleeding and some break in miles....also wondering if pivot is replacable through port where fork enters bellhousing...i REALLY do not want to pull the entire car back apart for a 20$ pivot ball...if it wont cause damage i can live with it and deal with it being normal “racecar“ noises as they say as i do have very stiff upgrafed everything...also old trans fluid was not shiny and not very dark at all, has tribodyn 75w-90 in now…hopefully you got it sorted or can get some answers man! But as always any help or input is greatly appreciated!

 

Hey man. I didn't activate the notification and only now I've seen the reply. Did you solve the problem?
In my case I haven't done anything besides putting damond street hardness passenger and gearbox mounts.
The buzz is still there, a bit diminished, probably due to the new position of the gearbox, and engine assembly, a slight shift downwards. The gearbox performs and behaves properly, shifts are smooth.
I'm still suspecting that one of the cables touches and slightly resonates in the firewall or along the routing somewhere and it has been diminished due to the new position of the gearbox, marginally lower.
Can't be bothered to investigate further while everything works fine.