[LaxMan]

I think your calculations might be a little off. (Then again so might mine)


It is true that the fuel pressure will be raise 12 pounds for every pound of boost. But that is not in addition to your 38psi.
The FMU is on the down streem side of the fuel system so the FMU will block the fuel going back to the take at specifiec pressure.

For instance. If you are building 3 PSI, the FMU will block off the fuel until it reaches 36 PSI and then start bleeding it toward the tank. The fuel regulator that is set at 38 is still making it hold 38 psi at the injector. Once you go to 4 psi the FMU blocks off the fuel until it reached 48 psi. Now the FMU is regulating the Fuel pressure and not you regulator. It basically is like the fuel regualtor is not even there at this point.

If you are going to run 9-10 PSI I would have to say switch to a 8:1 FMU calibator.