Hmm, I tried it with just the engine cover today and top down, didn't seem to notice much extra sound. I can imagine with the engine cover off I'll definitely notice, but the drives I'd like to have it are the ones where I have the top down.
I noticed without the speakerbox the plastic sits right on the engine cover. Has anyone tried engine cover off and top down, and know if the plastic window would take any damage/grime after extended use? Sadly, my six-year-old plastic is in absolute flawless condition, so I'm reluctant to take any risks
-David