More cooling is rarely a bad idea, but there are simpler ways to achieve it. The Bloody Wonder V2 had a sort of NACA duct cut into the top of the fuselage. You could easily do the same to the bottom of the power pod instead. Likewise, people have cut a hole in the power pod or fuselage and put half the cup of a plastic spoon over it to act as a scoop.
The whistle idea could be cool though. The little whistle might also be a good way to see how much airflow you get through somewhere too, just stick it in somewhere you're curious about, fly, and listen for whether it whistles or not.