Fitech Dual Quad fuel plumbing with return line

View attachment 1715921673 Here's how I did it.
No issues after several hundred miles.
Do you mind telling us what you did? I cannot tell from the photo. You seem to have fed both inlets from one pump, right? What did you do with the returns? Do they go into one line? What size? And, did you ever measure the back pressure on the return line?