my opinion on that setup is two fold. number one, i'm not a "fan" [pun intended biggrin] of aftermarket fans. they never seem to live up to their CFM output, and NEVER last as long as factory units. second, those type of shrouds should, in my opinion, have a couple of trap doors that would allow airflow at speed to assist in the cooling process. just my blathering, your mileage may vary.
beer