Okay awesome thanks a lot for your help guys ill keep an eye on the fuel rail pressure and see what happens. The previous shop when I asked how they test the injectors didn't really have a answer they said it's not much of test but they seem good it was my first time going their looks like I won't go back their.
They only checked balance rates then, that doesn't tell the condition of the injectors. You need to preform a return test. The dealership can do this. Tell them it's programmed so that they don't try overwriting your ECM with the latest GM file.