I don't' know of any supplement company large or small that would reveal their manufacturer.
And what exactly is a "high quality manufacturer" and if I revealed any of mine how would you know if they were high quality or crap?
Unless you're in the supplement business I don't know how the average person would have any clue to what a good manufacturer is, anymore than if you told me who manufacturers parts for Toyota. That info would be pretty much worthless to me unless I was in the auto manufacturing business.
As far as research chems companies go, most of them are "home brew", they are fairly small operations that are ordering their raws from China and bottling it up themselves. The reason being it would be hard to find a legit manufacturer to do it for them, of course I am sure there are some small shady ones that do.