No issues whatsoever.İ have been running this exhaust with a custom straight x pipe,when in open mode its very loud and has a little raspy but in a good way,and no drone in any rpm other than 2k rpms.Remember i am cattless
When in closed mode,there is virtually no drone.Just like stock and sounds kinda like e46 m3 with stock exhaust
When in auto mode,it opens and closes the valves with your desired rpm and acc pedal sensivity that you can adjust with their control unit.
Just call me anytime when you want to listen the exhaust