I didn't read the three p[ages of comments because the initial assumption is wrong.

Mufflers do not cause drone. The system causes drone. Similar to tuned headers or a tuned intake tract, the exhaust system has resonance and when the engine pulses excite that resonance, you experience drone. I've been in a few Men's rooms where it was easy to excite the resonant frequency by humming the right pitch. One I remember was at my old job, where the room was tuned to low "G".

So if mufflers do not cause drone, why do so many of these solutions work? Because they change the resonant point or else dampen the resonant peak's resonance to the point where it's not objectionable.

I suppose a louder muffler does have more of a tendency to drone, because the sound pressure (energy) is higher and more apt to resonate in an audible way.

Adding a crossover pipe or X-pipe can help too. I'd start there.

Dynomax Super Turbos 17748 and 17749 are my fvorites for 2 1/2" systems, if they fit. They are relatively quiet at idle or at low throttle pressure. With more power they take on more of an aggressive sound. I've received complimentws from strangers who tell me it sounds exactly right Upon startup, I was dismayed at how quite they were, but as the miles went by, they opened up a little.

So remember it's the system, not the mufflers.

R.