i thought i scarepd my bumper at first, didnt expect the car to be that low but realized it was my strakes

 

They are aerodynamic pieces that deflect the wind from hitting your tire, helps to create down force or prevent lift. I could be wrong though. I do know a few people who don't have them on their car (previous owner probably had one rip off and took the other off instead of getting new ones) with no ill effect. However it is much better to have something scape and find that it wasn't a problem, then to hear a scape after taking them off and knowing that you just f'ed up your bumper.