Scott Helme on Twitter: "The new Power Valve system has a DDE (Dynamic Drone Eliminator) built in to control the bass/hum/drone inside the car. Loud exahust but without the annoying drone in
some new ideas to reduce exhaust drone - 6SpeedOnline - Porsche Forum and Luxury Car Resource
Exhaust Drone Eliminator With Deep Sound - Paradox Performance Muffler
Exhaust Drone: What Is It and How to Eliminate It? – Pertronix