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is a slight reduction in exaust back pressure after the catalytic converter good or bad?

  • 2003
  • 911 Carrera
43 000

I have heard that a slight reduction of back pressure can be good for performance.   I was looking at the FD Motorsports exaust modification which will reduce back pressure slightly.  A bi pass is placed between the entrance and tail pipe on the stock muffler.  The attachment of the bi pass is after the catalytic converter.   Can this hurt the engine? The bi pass only diverts some of the exaust gasses from going through the muffler.  

The bi pass will not affect emissions since it's after the Cat.

Any thoughts?


Thank You.


Andrew H

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