Originally Posted by STItoEVOX

That might have been true for the last, non-HD model. But with this one they've totally revamped the audio capturing capabilities. There's not even a HI/LO setting like the last model. With the HD model you'll receive 2 kinds of backings for the mounting case: one will be solid for a waterproof housing; and the other is slotted for higher audio sensitivity. So if you want to hear that exhaust, for example, use the slotted backing. If you plan on reaching really high speeds or need it waterproof use the solid backing. Its actually pretty impressive compared to the non-HD version at how good it is of avoiding wind noise when mounted outside.

I'll try to figure out how to upload some of my videos to show you guys what I'm talking about.