fuel pressure what psi to use with supercharger??

I dont think you should be worried about buying a fuel pressure regualtor,

Your Fuel setup is arse backwards,

Theres nothing wring with usinf the stock FPR for blown setups,
The computer knows you have bumped the pressure up anyway and it sends different pulses to the injectors to make them flow lower,

From what I remember you get about 10 mins of pressure at what you set it at before the computer retards what you have done,
I remember reading loads of threads saying ajustable FPR's are a waste of time,

and why did you get a 255 LPH Fuel pump????? Thats overkill for your fuel setup,

You could have got a 155 or at the most a 190 pump and been fine,
Hell the stock pump works with 5 psi blowers,

From my experience, Id get a nice set of 30# Ford injectors, a 30# Mass air,
and leave your stock FPR,
You will be fine with the fuel,

And to check the pressure you need a Fuel pressure gauge that you can buy from Pep Boys for about $40,
Or you can get one that you screw into your schrader valve.

No you cant use a tire pressure gauge for this,
Id also sell your 255 LPH pump and replace with a 155 or 190, 255 is overkill for that setup unless your planning to run 14 psi in which case make sure you have a 40 Lb bag of speedy dry in your trunk, You will need it.

But seriously,

Injectors, Mass air, THEN fuel pump, apparantly FPRs are a waste, Id agree,

The Vortech FMU and stock Regulator are non-adjustable, and cannot not be made adjustable.

There are a few companies that sell adjustable FMU's if you need more fuel in boost.

If you install a AFPR then all you have to do it remove the upper intake, and one side of the fuel rail, and remove 3 allen head screws on the regulator.

Do NOT check your fuel pressure with a tire gauge. Talk about being dangerous... You need a mechanics fuel pressure gauge, or an aftermarket one like an autometer.

Whenever your dealing with a supercharger don't be cheap about it because in the long run it might end up costing you more money.....

How much boost are you running anyways?

there is nothing wrong with a oversized fuel pump, since you regulate the fuel with the AFPR! stop listening to the internet racers who don't have any experience with anything.

I highly disagree with the comment about the fuel pump being too big. You definetly are running the right fuel pump. Get the Kirban fuel pressure regulator. You will want a base fuel pressure between 38-40. You will also need to keep running that FMU until you buy new injectors. The adjustable FPR will come in handy when you buy new injectors and ditch that FMU.

yeah thats a great pump for your set up...but i would get it tuned ASAP just to be sure you have proper settings and everything....you dont wanna have to drop another couple grand on a new motor if you just put that amount on the charger

you can never have too big a fuel pump the way our mustangs work is they have 2 lines a fuel sender and return line, any used fuel is sent back to the tank, so you can't have to large a fuel pump and it won't hurt your performance.

you can have your vortech fmu recalibrated to your injector sizes, this is possible by replacing the washer on top of the piston and it yields a different ratio, example 4:1, 6:1, 8:1, etc. The deal is if you buy a large enough injector you can ditch the fmu. An fmu is actual a cheap way to squeeze extra fuel out of your injectors when high boost is present opposed to returning to the tank.

To the original question, its possible to swap the fuel regulator while the upper intake is on the car but its extremely difficult and awkward. You fuel pressure from the factory is anywhere from 36-40psi with the stock regulator you can't adjust it what you see is what you get. If you don't want to goto an afpr, than I say stick with the fmu route. Also no one tell you and optimum fuel pressure to set your car at, the easiest way is to install some wideband o2's and check the air/fuel ratio for you I'd say 11.0:1 is about optimum the rule of thumb is the leaner the mixture the higher the octane your car needs.