I have a 2003 accord Euro 6 speed it was running the ATS5 gearbox.

About 6 months ago I had acquired a low km jdm DC5 R box and decided to swap the complete gear set and lsd into my case BUT swap the original 0.659 sixth gear from the factory box to allow for a gear to still be good for the open road cruising. I also had the k20a flywheel installed and a brand new heavy duty clutch pressure plate and release bearing

The workshop that did the job spent 16.5 hours of labour doing the job... But as soon as I got the car back there were noises. At idle it had a bearing type noise with the clutch out. And push clutch in it would go away. And then the other noise was like a grinding noise in any gear when you back off the throttle and are coasting with no throttle. Apply the throttle and the noise dissipates to not really noticeable.

From day one I let them know about the noise....
Anyway after waiting for then to look at it properly in the shop.. (months!!!) They finally took the car and pulled it apart.... 2 weeks later with very little communication my car is ready.....

The trail...
End of day 1 a Thursday
I get a call to say they have driven the car and had it on the hoist and listen to the noise and agree there is definitely a serious noise and they think it's got what sounds like gear lash....
I send a message after doing research about gearlash and k series boxes and every shred of info points to incorrect assembly... So I inform them that I feel that it seems that the job was not done properly to begin with....
End of day 2 Friday
Receive a text message
"Pulled it apart and all looks good as inside. It even measures up sweet. No gear wear. Choice"
Day 3 I reply with
"So that's good...but what's making all the noise then???? Do I need to replace Bearings????"
Response
"Back into it Monday. We have to do more study. Cant do much today."
I hear nothing until end of day 8 Friday
Only after I send a message
"Hey how you doing? So any update with my car is it sorted? Thought I would have heard from you?"
Response
"Got box back together but not in car yet. Only thing abnormal is it has destroyed 6th gear needle bearing collar. Nev seen anything like it. And it's the one from the original box."
I responded morning of day 12 tuesday
"Hi so are they sure there has been no damage to any other bearings???? Would it not be a good idea to check and replace the others if they have been compromised?
Response
"We have inspected everything. We are some other bearings regardless"
Day 14 message.
"Box all good. Brake lines done. Due for service or do you wsnt to do that?"

So I have my car back and it is all good no noises etc...
He then tries to tell me that they think that me choosing to use the original tall sixth gear is probably the cause of the bearing destroying itself??????
Then he goes on to tell me that honda in our country has never sold that bearing for 6th gear.....

My question to everybody is dies anybody know of anybody that has ever had or heard of something similar or has any theories as this all doesn't add up to me....

PLEASE ANY OPINIONS OR INFORMATION OR ADVICE WOUKD BE MUCH APPRECIATED.....