I have an 18" oval bodied Magnaflow. I really like the mellow yet aggressive tone it has. The 14" is noticeably louder and more aggressive. I have no drone at all BUT I have a side exit.
The dual exit out the back can tend to drone, especially if your towing!

 

The 24" one drones a good bit and like mentioned when I was pulling a trailer the drone was horrible.

 

You are both right and wrong on that one.

http://www.corsaperf.com/technology.aspx

I can see straight through the muffler. The side chambers are only there to cancel out the sound waves that create the drone in the cab.

 

awesome, thanks for the clarification. when I researched, I only got to the spec's of "chambered" and looked no further. I am already swapping out my intake for a 'closed style' Volant since I cannot stand the partial throttle whooshing noise anymore. This may be next up to bat once I start listening to some sound clips. ( yes, I usually do things 2x to get it right .... )