Hey, John....there's a separate forum section here created just for the show where that has been discussed and Brent (producer) says they are addressing the 'sounds' issue as well as others.
http://www.nitromater.com/forum/forumdisplay.php?f=13
I'd like to know when they will FIX the Sound editing of the cars. Getting old to be honest!
I personally don't think they CAN fix the sound. There is no way to properly convey what those cars sound/ feel like through a tv speaker. They could maybe get a little closer but it'll never be near the live "experience".