Thanks Bruce!
I just removed the catch tank and Carter feed pump and now I can maintain my target lambda all the way to redline under 20 psi of boost. Now that was fun
You were probably close with the feed to the 044 not being optimal. The intake line is 1/2" internal from the tank to the feed pump, so plenty big, but entrence into catch tank is only 7mm internal, so almost half that size. For the low pressure Carter pump probably a little too much of a restruction to get to full flow.
Feed to the 044 itself from the catch tank is 1/2" or about -12 iirc, but if there's only one restriction...
Now the 044 sucking straight from the 1/2" from under the tank works well, but at higher boost, the rising rate pressure suffers a little and doesn;t follow the boost pressure quite. That leads me to believe the 044 is somehow running a little on the edge in my set-up.
For now it will do, but maybe a second pump may be wise in the long run.
Thanks for thinking along all!