Originally Posted by Geoff-AU

I would disagree, drone is a single resonant frequency that is dominant.
Volume is not drone. You can have an exhaust that is musical and loud everywhere, that is not drone.

The HKS team know their ****. The Helmholtz resonators are PERFECTLY designed. There is an exhaust note, but the note's pitch follows the revs (unlike drone which is a single note that just gets louder and quieter depending on revs) and the HKS is not in any way offensive. It is a very docile exhaust at light throttles but once you open the throttle a bit it comes to life. I'm an electronics engineer by trade but I can appreciate something in a different field that has had some proper effort put into it by talented people rather than just slapped together and pushed out the door with a dyno sheet to show it gains power.