I second the motion: get rid of the pumps. As I understand it, the oscillating piston with flap valves in the pumps are unable to keep up with the high vibrational frequency of .45 DF engines turning 22-23k.

You are going to have a problem with a DF A10 and any fuel system (single or separate tanks) with main tanks located down near the wing and the cg: could be 4-6 inches lower than the carburators/venturis. Reminds me of my 45 DF Sabre with its tank mounted low-actually in the wing root center section. It will forever be difficult to consistently get the right amount of carb suction & pipe pressure. The amount of exhaust pressure transmitted to the tanks will depend greatly on the rpm and what type of exhaust system you are using. Are you using a standard exhaust mufflers, or some type of short (Weston) tuned pipe?

You might consider moving the tanks higher and more aftwards in the fuse to reduce the gravity gradient as well as the length of the fuel tubing runs. You could test that on the ground by seeing if external tanks mounted as high in the fuse as they could be possibly installed give you more consistent engine runs. If that helps, then reinstall the tanks high and aftwards in the fuse and balance the A10 with full tanks (using nose weight/battery packs, etc) and an aftwards as possible CG. As fuel burns off it should become more nose heavy.