fuel system questions

[blown4_6]

I finally got my 02 mustang back from engine builder. I have a few questions for you guys. When we started the car the fuel pressure is all over the place and Im not sure why. Tuning issue or what? I had extensive mods done to the car in terms of rotating assembly and a ton of head work. I dont know if the computer is trying to compensate for the difference in air flow from my last tune. I also need to know what kind of power the stock fuel line and rails are good for. I already have the 03-04 cobra pump in it and 42 lb. injectors. I just want to get it right before I take it to get it new tune, since it going to be about a 5 hr ride trailering the car. The last thing I need is to get there and they tell me its running out of fuel. The engine builder gave me the numbers from the flow bench and says the head job is capable of supporting 500 to 600 hp. Thanks guys for the help

 

[SaleenGT2001]

what mods do you have?? those 42's may not be enough. we need more specific details on the setup. cams, boost level, what s/c, etc...........

 

[RedBullitt]

returnless fuel system pressure seems to jump around sharply when you are using the gas, mine stays around 40-45 when im easy, jumps up to 60 with gas and a bit more with more gas (do have bap in there).
my friend has a return style on his cobra and it looks a lot smoother....
maybe your injectors might be running out of steam, what maf?