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.
By replacing two gaskets from the EGR system with these blocking plates the system can be disabled easily and effectively.
An improvement of the driveability will be directly noticeable.
For newer euro 3 engines it could be neccesary to modify the mapping, for euro 4 it is always neccesary.