Downpipe is a crucial component in the exhaust system of a turbocharged vehicle. Its primary function is to direct the exhaust gases from the turbocharger to the rest of the exhaust system and eventually out of the vehicle. 

Function and Purpose:

  • Turbocharged Engines: In turbocharged engines, the exhaust gases produced by the combustion process spin the turbocharger’s turbine, which in turn helps compress the intake air, increasing engine power. After passing through the turbocharger, these exhaust gases need to be efficiently routed out of the engine, and this is where the downpipe comes into play.


  • Flow Efficiency: A well-designed item reduces backpressure and increases the flow of exhaust gases. This can significantly improve engine performance, as it allows the turbocharger to spool more quickly and efficiently.
  • Heat Management: By efficiently routing hot exhaust gases away from the engine, the downpipe helps manage engine temperatures and maintain performance.

Catted Downpipes

  • Emissions Compliance: Catted downpipes include a catalytic converter which helps reduce harmful emissions, making the vehicle more environmentally friendly and often compliant with emission regulations.
  • Less Odor: They reduce the sulfur smell commonly associated with catless.
  • Legal Compliance: More likely to pass emissions tests and inspections required by law in many regions.
  • Reduced Noise: They tend to be quieter than catless, as the catalytic converter also helps to muffle the exhaust sound.

Catless Downpipes

  • Performance: Offer the best performance gains as they are less restrictive, allowing for better exhaust flow and potentially more power and torque.
  • Cost: Generally cheaper than catted as they do not include the expensive catalytic converter.
  • Sound: Provide a louder and more aggressive exhaust note, which some enthusiasts prefer.

If the vehicle is mainly for street use, a catted option might be a better choice. For track use, where emissions regulations might be less stringent, a catless option could be considered.
Performance Goals: Determine how much of a performance gain you are seeking. Catless downpipes offer better performance but at the cost of emissions and legality.

Audi downpipes
BMW downpipes
Mercedes AMG downpipes
Porsche downpipes