If you like the sound of a chambered muffler like a Flowmaster 40, look into the Pypes Street Pro mufflers. It's a similar sound, minus the loud drone at low RPM (at least on my application). Plus they're stainless, have a lifetime warranty, and are made by a FABO forum member (CCAS)
Here's a comparison video I took of my 340 when I swapped from flowmaster 40's to the Pypes Street Pros. If you're looking for best performance, you're better off choosing mufflers with a straight through design like some already mentioned.
