Some where in the archives is an old discussion about the drone that was driving everyone batty. What I can remember from it was the purpose of the factory designed exhaust was to eliminate the drone. Which doesn't show up until we went from the stock to aftermarket. I went to a 3" exhaust and couldn't find anything to stop or neutralize the drone. I even tried a high dollar special foam/lead insulator to no avail, w/most of my driving speeds being between 45 and 60. I ended up driving either too slow or speeding!