A recent purchase of a 2000 Dodge 2500 with the cummins diesel engine. So this may be a basic question. The truck at 60,000 miles. My question is I noticed the other day more "AIR" noise comming from the exhaust that before. I have owned the truck for 4 weeks, so I am by far not an expert with diesel engines or noise. Power and fuel mileage seem to be the same. Is this normal?