:lol: You guys are hillarious! Moving parts bite!
Anyways, shrouds are designed to speed up airflow through the radiator when your sittin' still or slow moving. Same as flex fans, draw more at low rpm, less at high. Improves Thermotransfer of heat in traffic.
So, if your experiencing heat up problems in the "waiting line" you may need one. But, once you nail it off the light, the speed of the car provides all the incoming air, so it becomes useless.
Where's your problem area?