[Ed Wright]

Rich, higher fuel pressure atomizes fuel better. Better odds of every cylinder firing every time. In the real world they seldom do. My GM Calibration Engineer friend was telling me the power & emissions improvements they saw when developing the LS1 engines when going from the ~ 36/46 psi fuel pressure used with the LT1, to the ~60 psi for the LS1.
I had to go to 42 lb injectors for my LT1 Super Stock engine, to get the injector duty cycles comfortable @ 45 psi. I started thinking about that. I went to 36 lb FAST injectors @ 60 psi. They tested the same there as the 42s @ 45 psi. On my old Dynojet chassis dyno, A-B-A testing, dialed the air/fuel ratio to the same 12.8-1 it likes on C11, picked up 9 hp at the tires. Obviously some misfires going on we could not here. My GM guy predicted "8 or 10", saying "They all miss some, all the time. Has to be bad to hear it."
I thought the gains had to be a fluke when I changed them. Changed them back (as in A-B-A testing) and it dropped back off. Changed injectors, tune & fuel pressure again, picked it right back up. Had to call him to thank him. LOL