You are correct, all pressure tests are at idle. I hoped that going with this specific pump, and increasing supply lines to 10AN from cell all the way through the pump, and 8AN out of pump to carb and return I would be "good" with respect to flow when accelerating or WOT for a 1/4 mile. Maybe not. When I upgraded and installed with return line in lieu of dead-head, I did install with a return regulator, although not new out of the box. It's a Mallory 4309.
Foam was pulled out of the cell a while ago while I've been a chasing this.
