I read posts for hours looking for an answer or similar situation but I cant find anything that seems to match up. I will start with a short parts list for context.
BLOX subframe mount
3" straight pipe
ACT ME2HDSS clutch
ACT streetlite flywheel
stock tune / drivetrain
pretty much 03 evo 8 otherwise (other mods not relevant to this issue) 136k miles

So, I just did the clutch and figured I would do fluids as well, my car was due anyway. I used mitsu oem fluids, MTF 75w85 and LSD SAE 90. 3qts in my trans, put 1 qt in my tc, drove it to the gas station in back, drained excess from fill plug, per the Jack's write-up. I am an incredibly paranoid mechanic, hense the HOURS of reading on my car. I drove around a listened very carefully to my car to very nothing sounded like it was gonna blow like an A6M Zero. The car was down for 4 months (long story and some 2 months of back order and a bunch of curve *****) so I cant remember every single sound it made but I tried to place all the normal creaks and groans she made prior.

Ive got normal drivetrain noise in 1st and 2nd that I always had but in 3rd and 4th there is an easily missed whine. I think I might hear it in 5th but I think it is road noise at the speed I am going because I have some noisier all seasons. the whine is only really easy to hear between 2000-3000 rpm and is much quieter in 3rd than 4th. It is only on accel and gets slightly louder up to 3k rpms. I wanna say its tc but I dont know if I cant hear it past 3k rpms because of the exhaust or its going away. no gears grind, no pop outs, drives smooth. I dont feel like its death whine because I dont hear it in 5th or at high speeds. There is not grinding but I dont recall ever hearing it. I am wondering if its only im 3rd and 4th because those are my most frequently uses gears.

https://youtu.be/Au8fOnZ1uNQ
https://youtu.be/YKG6YSRvyaE

the sound in the beginning of both of these videos, before the sound of doom and apocalypse begins, is the closest I can find to the whine im hearing but mine is MUCH quieter. I dont think I could pick it up on video. Normal? Should I add fluid? Rebuild? Sell it and move to the country?

Thanks for bearing through a long post and any ideas about my car.

 

have you checked the t/c fluid level since the whine started?

 

i did and added a little more, doesnt seem to have changed much, I drove to work with the extra fluid in it and i plan on checking it again when i get home.

 

sounds like the transfer case to me.
but odd that it all of a sudden started after the clutch install

i hear that flywheel rattle too...

maybe get up on a lift and see if you can hear if its the transfer case or the trans

 

im gonna head to the dealer and pick up some more mtf and try to add a little in the morning then i got an appointment at 4D engineering to put in on a lift and have them listen to it because im stumped

doesnt sound like clutch noise, i had a 6puck before with a loud rattle and i was certain to use loctite and torque the flywheel to spec so my best guess is maybe trans. i added 3qts but maybe i need to put a tiny bit more. I appreciate the ideas

 

Always pump the tc from the bottom, then drive then pump again

 

funny enough, t case is just fine. my noise is my transmission as I found out this weekend..