If im not mistaken the ecu will help tune and regulate the air to fuel, ive heard the ecus do a decent job at tuning itself with small mods done to it, my thing is that ive heard that the stock injectors are already maxxed out pretty much, so if i were to throw in a small cam or possibly just a tune it would cause injectors to go bad fairly quickly and i would have to pay for stock set that im gonna change out farily quicker, even if i gain 1 mpg it would be a win, small things add upApples to oranges, injector placement is different which affects both differently. Can the 6 hole injectors atomize fuel better, perhaps, but even so it’s negligable at best, especially in the older pushrod motor.
Also, the ecu will not be able to adjust to the bigger injectors. The ecu expects x amount of fuel given a pulse. With bigger injectors more fuel is injected given the same pulse time. The ecu cannot adapt to the difference in fuel flow and will run rich. This is evident in the mustang world when Ford switched from 19 to 21 pound injectors in late 01. The model years with the 21 pound injectors ran rich in stock form because Ford did not adjust the tune.