A drone from a new muffler is loud, continuous, monotone sound that comes from a muffler. A droning sound usually occurs at higher RPM's when you're giving your stang more gas. Think of all the little honda rice rockets on the road that have that annoying, constant, high pitch sound to them....well, with the mustang it's not so much high pitch, but a lower pitch sound. The key in the drone is the constant, monotone sound that doesn't change.

Ever been in a warehouse where one of the flourescent lights is giving off a constant, unchanging buzzing noise? That's a drone.

 

If drone is an isssue, save up the extra $ and go with Corsa.

I've had both the Borla and Corsa systems on my 4.0L, and the Corsa's sound better overall, as well as totally eliminating any drone.

 

I have the Ford Racing Stingers you all are talking about.... about 10k on them. And yes, if you are on the highway for more than 10 miles at 65-75mph... you will want to fling yourself on the highway because of the mind numbing drone... Im looking into some resonators really soon..

So why do we buy them knowing they will drone? good question, but it has alot to do with how well they sound at any other mph or idle. They sound about as good as it gets for our car.. heres a vid of mine at idle, and a 0-90mph take off... you be the judge
http://www.youtube.com/watch?v=4PcdqpPkQiM

http://www.youtube.com/watch?v=WDXKLsKzaII