i find no flaws here. :)

generally, if you're watching both battery voltage and fuel pump voltage via the datastream, fuel pump voltage will almost always appear smoother. could be due to capacitor filtering inside the ECM for each channel's A/D circuit itself being different or just that the fuel pump tends to get a cleaner source of power, but i have yet to see a vehicle where fuel pump voltage looked noisier than battery voltage. GM may or may not have realized this as well and chose to use fuel pump voltage rather than battery voltage for injector corrections.