Straight-through, or flow-through, mufflers have perforated baffles and packing material that provides a conservative level of sound absorption while still keeping sound output moderately loud. Glasspack mufflers perform similar to resonators due to their design and lack of sound-absorbing packing material, so they tend to be louder and higher pitched. For compression-ignition (i.e., diesel) engines, the most commonly used catalytic converter is the diesel oxidation catalyst (DOC). This catalyst converts particulate matter (PM), hydrocarbons, and carbon monoxide to carbon dioxide and water. These converters often operate at 90 percent efficiency, virtually eliminating diesel odor and helping reduce visible particulates. These catalysts are ineffective for NOx, so NOx emissions from diesel engines are controlled by exhaust gas recirculation (EGR).
Rattling or knocking noises from your vehicle are the most common signs that you need a new exhaust. Any rust on the exhaust can also be a sign that an upgrade is due. When you bid we pre-authorize your credit card for the service fee (this helps prevent fraud). If you win the auction, your card will be charged for the service fee and you pay the seller directly for the vehicle. If you don't win, your existing pre-authorization will be released.
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