Hi all:
I am installing front volvo calipers and rear 323i calipers on my 316 with a Wilwood Bias valve on the rear brake line to adjust the rear brake bias. I have seen on parts diagrams a part known as the brake pressure regulator control valve. It is under the master cylinder and has a black metal housing with a circular can-shaped item underneath it. Can I remove this item and put the bias valve in its place, or is it necessary to keep it in? Thanks in advance.

oh my 81 320i, that pressure regulator is attached to the master cylinder, and then the single brake line (that goes to the rear breaks) goes into that regulator/cylinder-looking-thing.
if your putting on an adjustable brake bias valve, i don't see any need for that rear brake pressure regulator.