Regulator placement -- EFI setup

You guys are losing me and I am an engineer who has published papers on fluid flow. As long as there is minimal pressure drop due to flow from the regulator to each injector, all injectors will see the regulated pressure. At 1400 HP, there may be enough fuel flow that you need 1/2" tubing (haven't calculated), but most people should be fine with even 5/16" tubing. In current cars, the regulator is at the tank and most use 5/16" tubing to the engine.

If the fuel gets hot and turns to vapor in the lines, you could get a distribution problem, but unlikely at >50 psi, especially once flowing. With smaller tubing, the fuel passes thru the tubing faster so less heating.