Might want to start with your PCV system as this issue has been discussed numerous times. Below is a link to a good discussion, but in summary you should use have a low & high side OCC setup, retain factory flapper on high side, and recirculate the high side to a vaccum source (single turbo filter or turbo inlets for twin turbo setups)
Dual Catch Can - Why you want to do it | BMW - SpoolStreet
Also here is a diagram of my setup currently, hope this helps.
