I was told by the folks at GAMI that each letter size (an “A” to a “B”) will change the fuel flow by ½ pound per hour. .6 gallons per hour is about 3.6 pounds per hour, so yes a change of GMAI injector sizes can improve the equalization of the cylinders.

 

Lynn Farnsworth

 

 

You have classic TCM lean cylinders (1 and 2) but the left side peaking first together may be a good clue.  I'd certainly look for an induction leak on the left side then right side (I can't recall if your engine is Turbo or not).   The 0.6 difference seems reasonable so I'm not sure any GAMIjectors would necessarily help this particular problem.  I would definitely start looking for leaks, fuel stains, open sniffler valves and any tiny induction leak especially at clamps and couplings.  good luck.