Found this over at Flowmasters site.
http://www.flowmastermufflers.com/advantage.html
Course they are defending Chambered so lets hear the other side of the story.
One vs the other. Which is best???

 

yawn, repost

it all comes down to personal preference in tone/note/volume

 

It all comes down to the dynamometer. Everyone has opinions. But what counts is the science.

 

x2. Unless your very very serious about every 1 horsepower, its not a big deal. However the performance optinions are out there. Chambered mufflers are hollowed out mufflers with walls and baffle plates, where as a straight through or ceramic muffler is straight. Which one sounds like it would flow better for top performance? Thats right, the straight through design. However your only going to notice it on a dyno, or if you tow 8,000lbs.

Theres other personal reasons to go with a straight through over a chambered muffler, chambered mufflers are mostly aluminized steel ( will rot & rust ) and the plates can break off, thus ruining the sound.

 

Bingo. That was as dead on as it gets.