As far as the o.e.m. wing goes, I've seen 2 design types, so far, underneath. They each had a different trough design. I'm 100% certain it was due to the tonneau cover, in this case.
They are both designed to work with the front splitter and the package was developed with visual cues from the Craftsman Truck Series; then later developed and confirmed through wind tunnel testing.
The O.E.M. wings reduce drag, reduce lift and cleanup the air near the tailgate. I.o.w. they were designed to work with the tailgate installed to deal with air up and over the cab, and tailgate turbulence.
As for the Daytona Wing vs the O.E.M. wing for functionality...The O.E.M. wing works with the SRT-10.