Plumbing your mechanical fuel pump
Surge tank in the front (is strongly recommended)
Starting from the main fuel tank, plumb the lift pump inside the tank to the surge tank using either OEM line or -6 (both are fine) to the surge in the front of the car through a 100 micron filter, a stock pump or small Walbro 255 for example flows near double when its not under pressure.
Then run a -10 line (up to Kinsler 700 Tough pump series 1, series 2 tough pumps use -12 inlets from 800 - 1300 pumps, and you can go -16 for the bigger 1300- 1600 pumps) from the bottom of surge tank to inlet of the fuel pump as mentioned.
Then from the outlet of the pump you usually use -8 for the series 1 pumps and -10 for the series 2 pumps, through a fuel filter 10 micron, to injector rail, or at least filter before regulator. (Kinsler regulators are high precision and calibrated and will be impacted with any foreign matter larger than 10 micron).
Then continue the same back to the surge tank (-8 or -10 whatever size went into the rail) Then from surge to main tank, preferably -10 or -12 so you can vent the tank and not build a vacuum when the mech pump is pulling more than the lift can supply. (the line should be big enough to allow fuel to travel one way and air to travel the other way ideally).
For Surge tanks in the back (if you must) of the car Larger surge recommended, the higher the better unless you run a prime pump then it does not matter. Run a lift pump from main tank to the surge (oem line, or -6 is all that required much like the tank in front system above)
Then you run 1 -10 line that loops around to the main feed with the prime pump helping that main line being -16 to stay pressure positive.
It's a big line but fuel surge tanks in the back cause main fuel lines to cavitate and they need all the help they can get.
-16 goes to the main mechanical pump the other comes out of the surge into an inline pump (044 for eg) then through a high flow check valve and tee's it into the main supply line, from bottom of surge to inlet of fuel pump.
The main supply line needs a check valve before the prime line tees in, and a 100 micron inline filter after the prime but before the pump.
Then run a -10 line (up to Kinsler 700 Tough pump series 1, series 2 tough pumps use -12 inlets from 800 - 1300 pumps, and you can go -16 for the bigger 1300- 1600 pumps) from the bottom of surge tank to inlet of the fuel pump as mentioned.
Then from the outlet of the pump you usually use -8 for the series 1 pumps and -10 for the series 2 pumps, through a fuel filter 10 micron, to injector rail, or at least filter before regulator. (Kinsler regulators are high precision and calibrated and will be impacted with any foreign matter larger than 10 micron).
Then continue the same back to the surge tank (-8 or -10 whatever size went into the rail) Then from surge to main tank, preferably -10 or -12 so you can vent the tank and not build a vacuum when the mech pump is pulling more than the lift can supply. (the line should be big enough to allow fuel to travel one way and air to travel the other way ideally).
How big do I need my surge tank to be?
By calculation you work out the engines fuel consumption per minute (static fuel which means your full injector flow with 100% duty cycle) and divide by 6, that gives you 10 seconds at full throttle (more than you will ever be on full throttle without getting off it) for example 6 x 2400 cc injectors might flow 2600 @ base pressure of 80 psi, is 15.6 liters a minute, then divide that by 6 which gives you 10 seconds of running at 100% static duty being 2.6 liters.
10 seconds is the longest amount of time you will be using full throttle at full duty cycle being the worst case scenario, the whole time your lift pump is catching up, and sure the larger the surge the better but skinning the cat this is logically all the capacity you will need and some to give you some numbers to put your thoughts into perspective.
I hope this helps :)