as I did a lot of R&D regarding the power steering stuff this year.
The one and only solution looks like this.
I promise you - it's 100% rock solid:
Step 1) With the Macht Schnell pulleys I was able to do some laps without a boiling oil.
Due to the reduced ratio of the MS pulleys the keep the temperatures a little bit out of the power steering system.
Step 2) To get it really rock solid even during hot sunny days you'll need an additional power steering cooler.
If you look at the BMW GT4 power steering cooler you'll see that it's much larger than the stock e9* M3 cooler. They didn't change it for the racecar without reasons.
But the GT4 power steering cooler is way too expensive for what you get.
That's why I solved it for a little bit differently.
Here's my solution. This cooler here is added "in a row" to the stock one.