[Luce]

A 5-10 PSI pressure drop is really a non issue on a EFI engine. Mickmate's calcs are for carburated engine, and that's a totally different animal.

I would also add, it's more important that the return line be of sufficient size on an EFI engine in order for the regulator to be able to return enough fuel at an idle to function.

Here's how to test if your lines are of adequate size. With the engine off, run the fuel pumps and turn the regulator all of the way down. How low will it go? That's the maximum back pressure of the return line( it may be less, and the regulator is the restriction), and if the supply line is of the same size, length, and roughly the same amount and quality of bends, you can assume it's equally restrictive and adding that much work to the pump.