I am planning on Magnaflow mufflers when I get around to re-doing my exhaust.  A couple of guys I know have recently switched from the chambered Flowmaster type muffler to Magnaflow mufflers,  and the general consensus is that they sound better both inside and out.  One was a '57 Bel-Air and the other was just a stock '05 Silverado.  I have ridden in both vehicles,  before and after,  and I personally love the sound they have now.