What is the difference between partially open and fully open?
From factory some cars keep the valves only partially open in "loud" modes.
When the controller is ON, the valves will now be 100% fully open.
The sound difference between partially open and fully open is not that noticeable, however the major difference is not how much but when they are open.
While the valves are sometimes open or partially open, they do not stay open all the time even in "loud" modes. They close in certain RPMs, throttle positions, gears, speeds etc.
The Exhaust Controller keeps the valves 100% open in any drive mode all the time!