exhaust drone/harmonic resonance

Any updates??? For a drone free muffler with performance sound. I haven't ordered anything yet.

Totally different application but due to them advertising "No Drone" on there 2500hd mufflers maybe some of there car mufflers are drone resistent as well. I did have to replace the muffler on truck and used a flo-pro 2504 and it is drone free as advertised.