This is a simple drawing of a Holley Dead headed Fuel Pressure regulator. the fuel comes in the bottom of the regulator & goes up through the spring & then around the Check ball through a .220 orifice. The fuel goes up through the orifice & then down & out one or both of the exits.
The sping & screw on top push down on top of the Diapragm, which has the rod that pushes down through the orfice to un-seat the ball from the bottom of the orifice & up comes the gas.
This is one of my old Holley Dead Headed regulators. In the picture on the right, I turned the body of the regulator UP so that you can see that the gas comes up through the Orifice then down to exit the sides.
This is a Mallory unit that I had laying around. as you can see its pretty close to the same as the Holley unit, only everything its billet & much nicer. the Orifice appears to be larger as well, but I could not get my caliper in it to measure it.
I bought a N2O filter, filter to filter the N2O as I fill the bottle. as usual I had to take it apart to check it out & see what was in it. its quite simple, just a little screen in it. Nothing fancy.
Here are the Bottle valves & pickup tubes from my N2O bottles. I had to rotate them a little bit so that they are in the bottom of the bottle because of how they sit in the Trunk.