My V-6 4.3 has 30 lb injectors stock & so far I made 386 HP @ the wheels & have not run out of injector yet. Turbo w/21 PSI
And like you I have a fresh set of 36's ready to install.
What size are the stock injectors on the 4.2,are the years all the same?

MBHD


12 port SDS EFI