they do what they claim to "help keep the airflow attached" but test after test on here has proven that they don't help the aero behind the car. i do have a friend that placed them under his car about 6 inches from the front of his belly pan and it reduced the "floatiness" of the car when dealing with crosswinds (and passing semi-trucks, when dealing with the air deflected to the side by the flat front)
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