Advanced Flow Engineering has designed three different air intake systems to meet the needs of your diesel engine. For the largest possible performance gain we recommend replacing the entire air box and intake tract with the AFE Stage 2 open element air intake system. If you want to maintain a factory appearance the AFE Stage 2 Si sealed air box provides quiet power. For a great value the AFE Stage 1 air intake systems adds instant horsepower and torque for stock to mild modified turbo diesel engines.