I haven't found an example where it has been tried with the purpose of reducing drag, so the results don't really apply (they didn't measure what I needed measured... at least that I could find publicly).
If I'm right, though, it might be a moot point. It would be a pretty involved install (cutting a big hole in the firewall and other obstructions, making it water-tight, keeping the ducting out of the way, etc.).
man I wish I had access to a wind tunnel...
I just might have to build one of
these (low-speed wind tunnel, courtesy of NASA)... I checked it out and I have everything except the plexiglass and fan... and I can just adapt a computer power supply and computer fans to go in place of that... hmmm...
