I have them also and they sound great - not quiet, just not extreme. There is a video of a drive in post #137 at the link below. There is some acceleration at the 3:33 mark with little to no wind noise. The audio doesn't do any of these cars justice - you can't really hear the true sound on computer speakers... As for your question about how they're made differently, the baffle is simply longer than the standard pipes. At the end of the video below there is a walk around and you can see the elongated baffle.
First Pics of ERA #795
Kevin