I can certainly hear it with the windows up. In fact, if I put my right foot down while using option 666 with the windows up, folks on the other end can tell I'm driving something really special -- even at relatively low speeds. Let's not even talk about the aural bliss I experience with the top down (I have a convertible) -- absolutely wonderful!

Only one drawback -- when my girlfriend calls she can always tell when I'm driving "vigorously" since PSE is modded, so I get to hear her whine about how I shouldn't drive so fast all the time. A little annoying (my girlfriend, not the PSE of course), but I luv her anyway . . . she helped me to finalize all my options, PSE included. Great car, great gal! I plan to keep 'em both.