The classic chambered looks like a good design, ought to sound nice too.
Only problem is the largest they make is 3" in/out.
I have 3.5" LoBak sprint car mufflers on my 427. They have a 4" core with a center tube and 2 spiral deflectors. No packing whatsoever so the sound or performance won't change over time.
They may be a bit loud for some, especially on my 12.5/1 motor, but I love them. Just have to wear earplugs on a long drive.
