that piece actually may serve some purpose. By the looks of it, it will direct air flow through your radiator and AC condenser. Without it air will take the path of least resistance and blow up top over it. I could be wrong in how it's designed though since I never actually seen one removed.This. I wanted an engine cover for my 1.6 but I changed my mind. I even removed the plastic piece that goes over the core support.
Maybe it's better it didn't pan out as I am sure it would of cost an arm and a leg to be able to afford it.I don't believe so.
I think there was going to be one and it never panned out:
Versa Intake manifold photo & dyno results : Versa Engine, Drivetrain and Tuning