Does anyone out there know the difference in output between the Lightning/Harley Davidson fuel pump and the stock pump for the 5.4L not supercharged?

 

More than a small difference.

The Lightning and HD trucks come with a dual fuel pump setup and a boost sensitive pressure regulator. In addition, their PCM controls a switching circuit that supplies reduced voltage at idle and part throttle to slow the pumps down so that they don't generate too much flow and pressure except when under boost.

Go to Got Pressure http://www.got-pressure.com/yabbse/index.php where you will find a source for an aftermarket pump that will fit your requirements.