On the dash up by the windshield, there are these what look to be tweeter covers. Are there actual speakers under them and if so, what gives? There are no speaker wires going to them from the head unit. Im wondering if I could actually stick some small tweeters from a component set in there and see how they sound.

 

They're real speakers and they work well. To demonstrate, turn up the music and then bring your head down below the dash to hear the difference in trebble.