From the factory, as I was told, GM tries to spary the back side of the closed intake valve... which aids in evaporation and keeps you from hosing down the cylinder walls...
too far early and you puddle up, too late and you wash the cylinder walls and rings down with fuel...
Just right and the heat helps with fuel evaporation, and allows it to all burn just right.
My thought would be just to follow GM's practice.. move back the injector timing to shoot for the back of the valve still...
I may get time to play with how it works on the dyno tomorrow with a customers car., no guarantees... I'm still trying to find out for sure if the guy wants me to tune his vette tomorrow or to wait till next week