You suck.wikipedia said:EGR deletion
EGR deletion in diesel engines is considered justifiable by a wide range of people, including the environmentally conscious. Although deleting the EGR system results in increased NOx levels, hydrocarbon emissions, Particulates, Carbon monoxide and Carbon dioxide are drastically reduced. Furthermore, EGR deletion results in an increase in fuel economy as high as 25%. Exhaust gas recirculated back into the cylinders adds wear-inducing contaminants and causes an increase engine oil acidity, which can result in an inefficient, poorly running engine. The increased level of soot also creates the need for diesel particulate filters to prevent environmental contamination.