Exhaust diameter question
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    1. #1
      Junior Member
      Join Date
      Sep 2019

      Exhaust diameter question

      My car is a T5, with Polestar tune, and a BMC air fliter. I'm adding a high flow muffler, and wondering if I should be using a 2.5 inch muffler, or a 3.0 inch muffler. I'll be retaining the factory resonator, and factory mid-pipe, only replacing the muffler/tips.

      I already bought a 2.5" inch (63.5mm) vibrant muffler, thinking that for a 2.0L turbo with about 260hp/300torque, 2.5 inch should be sufficient. But I just found out the factory piping is actually 65.5mm (2.578"). This means a roughly 2mm reduction in pipe diameter, going from factory mid-pipes, into the aftermarket high-flow muffler.

      Would that be ok? or should I actually be using the 3.0" version of the Vibrant muffler? My concern is if that 2mm reduction in pipe diameter going into the muffler could create untended restriction/back-pressure.

      Thanks for any info.

      Last edited by AJS1KR; 06-03-2020 at 01:33 PM.

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