If it's not sealed to the air cleaner it can reduce the air drawn through the radiator a wee bit. It shouldn't make more pressure than the air moving through the grille.

Electric fans with shrouds? What kind of fans? Some of the cheapies (and not so cheapies) don't flow enough air to keep up with highway speeds.

We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon