First track run - less than exciting....

I guess to ask it another way....what is it about the EFI intake that means the lean out issue doesnt happen?

Is it the amount the intake flows per minute, or is it air speed, or a combination of both?

It's the EFI. The fuel is injected at the port at the right time, amount, and place and the intake has only air to run through it. One of the many advantages of EFI. We have to rely on the design and efficiency of the intake on a carbed engine which in this case sucks so the dual quad top may help the fuel distribution.