Which muffler brand makes the best sound?

 

It depends what you call "best sound".

If you want some big booming exhaust that sounds like you got a subwoofer behind your head, then any of the so-called "straight thru" mufflers from HKS, Stillen, Greddy, etc.. wil do. They all resonate dramatically around 2000-3000RPM... But that same resonance (which is created by gas pressure waves bouncing back and forth on the inner walls of the muffler and constructively expanding) might upset flow characteristics and make more backpressure on the low end which will then reduce your low end torque...

If you don't want booming sounds, then make sure the actual sound chamber is relatively free flow and about 20"-24" in length... I had a custom fabricate muffler installed with a 24" sound chamber and 2.5" inlet pipe. The outlet pipe is 2.0". This configuration left no noticeable drop in high end acceleration, a lot quieter on the bottom end....