I've tried it. No measurable difference. I also pulled the weatherstrip that seals the back of the hood to the cowl. All I got for my efforts was a filthy engine and hood insulation. I even tried pulling the fan and shroud to see if it was a restriction at high speeds. Total failure. My testing was at the race track in 95º heat.
(It may help while sitting in traffic but not while at full throttle on a track)

Les