bjuice

travis i would stay away from any tee or "y" as they are sometimes called.
i run a Magnafuel prostar 500 pump..here is how i set up my system..

#12 line from tank to pump, #10 line from pump to 4-port barry grant regulator..mounted the 4 port regulator on the intake in front of the carbs and ran #8 lines to carbs form the REGULATED 4 Ports,,,the 4 port regualtor has a FREE FLOW UN-REGULATED port that you will run the NOS thru...NEVER REGULATE A LINE FROM A PORT THAT IS ALREADY REGULATED.....thats why they have the free flow port on these 4 port regualtors

The cheap little holley silver regualtors is all you need for the nos gas selenoids..there are many ways to plumb the 3+ stage..to start with your going to bring the NOS feed off the UN-REGUALTED PORT off the 4 port regualtor....they make a fuel log type set up for 3 stages plus....basically the regulators sit side by side on the UN-REGUALTED log...then you can plumb off each regualtor to the GAS SELENOID YOU choose...

i will go ahead and say this..wet flow each regualtor under WOT conditions..all ya gotta do is get you a 3/8 gas rubber hose with the correct size female AN fitting for the regualtors you have ( A #6 female A/N push lock works good here)..then on the other end of the hose push in your NOS GAS PILL and place a small circle clamp around the hose holding the Pill in place...get you a small pail i used a bathroom garbage can...point the end of the hose with the gas pill in the can and have someone press the button to activate your gas selenoid for the stage you are testing...watch your fuel pressure gage on that regulator and see where the fuel pressure drops and adjust from there...once you have it where you want it..then take out the fuel gage and go to the next regualtor..

i have seen too many people say they flow their systems and come to find out they had it dead headed..do not make this mistake..its not a true reading..most of the time there is a minimum of a 1lb difference if not more from dead head to WOT..
hope this helps.

Oh yes...you will need only one return line from the fuel pump to the fuel cell...#8...i would also make my vent valve a #8 instead of the factory #6 most off the shelf fuel cells come with..you are also going to have to buy you a #12 male fitting to bring out of the tank to pump...

Brian