Any quality rad shrouds being made?
The whole idea of the shroud is to allow the fan to direct air flow through the radiator efficiently without losing as much air flow as possible.
They focus airflow through the entire radiator as compared to just the area that is covered by the traditional fan, creating a vacuum that pulls air across the entire surface area of the radiator, thus increasing cooling.
An un-shrouded fan is moving air through only the portion of the radiator equal to the surface area of the fan.
The same principle applies such as in wind tunnels, the turbine or fan is mounted in the entire diameter of the tunnel for maximum efficiency and air flow.