Loading injector info

I am entering injector information into my MegaSquirt ECU. The injectors I am using are Ford Bosch injectors 0-280-150-403 the only info I could find on them was based on fuel pressure of 43.5. I am installing these on a boosted 2.3 at 20PSI.

Question: with the information for the injectors based on 43.5 how will this affect my tune if I only run at 39 PSI for fuel pressure?

If you tune the fuel table with the incorrect injector info, you will just "bake" in any errors. The car can run fine.

Not having the correct injector information may mean that when you request 5% more fuel, you only get (5% x 39/43.5 =) 4.4% (or something else) more fuel, so it might take a couple of iterations to get the fueling exactly right.

This also means that compensations that normally work might need different scaling, however it's likely to be close enough that closed loop can handle the rest.

You could try to determine the correct injector characterization yourself. Perhaps there is a test mode, or you (or someone) could rebuild the firmware to allow injector testing.