A 7psi mechanical fuel pump has a tough time putting fuel into a carb under 10 psi of boost. If you reference the back of the diaphragm to the boost pressure you fool the pump into thinking it's still in the real world. Sorta like putting blinders on a horse. The danger is still there he just can't see it. I'll try to dig out one of the Stude pumps I modified for the '54. There was an undrilled boss on the last one in just the right place.
