You might be ok without the air ducts being functional, i dont remember seeing any on models other than the M-Sport's. They do point back over the front brake disks, but i also thought they were to do with aerodynamics and the aero-curtain BMW talk about here:
http://www.bmw.com/com/en/insights/t...odynamics.html
I'm probably wrong tho, but it does seem weird that all M-Sports i've seen have these ducts, but say a sport with the same performance might not.