If I install a AFPR, I need a guage too, correct? I can't seem to find a regulator/guage combination. Do I just adjust the regulator to the setting I desire and assume it's correct? I thught I saw some pictures of a regulator and guage mounted on the fuel rail. Has anyone done that?

What about the theory that an AFPR is useless because the PCM adjusts for it- What if fuel line pressure was dropping at high RPM's due to engine modifications, wouldn't a higher line pressure help accomodate for that?

 

You need a gauge to set the AFPR. It doesn't have to be a permanent gauge... once you set it, it shouldn't change. You can get a 2" gauge on a rubber hose called a "test gauge"... you screw it on the Schrader valve to check the pressure. Or you can get a small gauge with a short metal pipe that screws on the Schrader and stays there. I think Accel makes these. The AFPR doesn't go on the Schrader valve, it replaces the stock FPR on the back end of the driver's side fuel rail.

Third option is a permanent in dash gauge, electronic with a sending unit attached to the Schrader.

There is no reason the stock fuel system should lose fuel pressure at WOT or high RPM. If it does, and you are under 400HP, there is a problem with the pump, filter or regulator. If you are over 400HP and losing pressure, you should opt for a bigger pump, not bumping it up using an AFPR. The AFPR raises pressure by limiting the fuel return to the tank... if you aren;'t sending enough fuel with the pump, an AFPR isn't going to make the pressure any higher.

Where an AFPR can help is when your injector size is marginal. Raising the fuel pressure 20% will gain you about 10% extra fuel flow. The alternative would be to simply put the correct size injector in.