What fixed it for me is the Bimmerworld powersteering reservoir + do88 powersteering cooler
I'm not as fast as dogbone or some other track rats here, but I think my pace is decent and I'm running 295 square Nankang AR-1, so there is a decent amount of stress on the car
I even did some sliding around and tossing the car around today, and no PS fluid spraying through my hood vents.
Wrapping a sock around the stock reservoir didn't help - the fluid would just drain out anyways.