The EGR system has the function to lower NOx emission. Unfortenately there are a lot of disadvantages, such as increased soot, CO and HC emissions, lower mileage and less power.
Also obstructed intakes caused by severe sooting is a big problem.
Placing this plate in a passage from the EGR system, it can be disabled mechanically.
An improvement of the driveability will be directly noticeable.
Note: It is neccesary to modify the mapping.