QUOTE(Cairo94507 @ Feb 13 2019, 07:11 AM)
Probably better than running with nothing in the rear.
Not better aero, that's for sure! It will, however, serve quite nicely to trap heated air under the engine/transmission. So it will help warm your engine up more, especially once it is already warmed up!
No valence is far better for cooling than any stock valence.
--DD