well i searched on this but didnt really find my answer. why is this nessesary? i have a directport nozzle kit and i can pull it off the shrader valve on the rail. i guess the FPSS can go after the rail before the noid. my thing is why does it matter? why would my pressure drop? would it be because of a bad pump? or would adding the extra spray realy suck down my pressure? or would this be more for a dry kit since the injectorshave to work harder?

 

You could have pump failure, regulator failure, bad injectors, and so on. There are many things that could lead to a fuel pressure problem. You don't have to have one, but they are recomended.

 

Here is the link https://ls1tech.com/forums/nitrous-oxide/269412-tech-tip-fpss-how-adjust-y-have.html that talks about the fuel pressure switch.
Ricky

 

haha i dont know how i missed that ok so i think i have the hang of it now. basicly just incase you have a fuel dillevery problem it reduces the chance of a lean condition

 

be careful when using the shraeder valve off the fuel rail in your returnless setup... i saw issue on mine before i converted to the regulator on the rail... not meaning to scare you but i don't know how big of a shot your planning on running off the rail. what you will see is a fairly large pressure drop for a second ( which is a LONG time when hitting the spray) this will create a LARGE cylinder pressure spike.. which it will "hit hard" but you are in fact going way lean for a very short period of time.. you will see this on the dyno.. the reason is your "regulator" is at the tank in your filter.. so you ahve 8' or so of fuel line to fill when the fuel solenoid opens.. normally up to a 150 shot you should not have an issue but if you spray out of the hole and the car bogs on a stock bottom end you can loose a piston.. with the regulator on the rail you have inches to fill instead of feet and you will not see as drastic as a drop which will help with longevity and reliability of your system...

 

ok sounds good. i plan on doing the 125 shot that comes with the kit then i'm going to do a stand alone when i bump to the big 2 zero zero