Cat Back Exhaust

This part does not affect the base vehicle warranty.

mountune has many years of experience in engineering exhaust systems with the objective of increased power and response, coupled with an enhanced exhaust tone and appearance.

The mountune Performance mk3 Focus ST cat back exhaust system is manufactured from 2.5” diameter, AISI 304 stainless steel (EN58E) mandrel-bent tubing with lazer cut flanges. All muffler assemblies are robotically TIG welded AISI 304 stainless steel for long life under extreme performance and feature consistent internal diameter throughout the entire length of the assembly.

To ensure improved performance while controlling sound, each muffler includes a three-layer hybrid synthetic sound absorption packing that eliminates droning, booming, and other undesirable tones. Tubing diameter also has a major impact on sound quality and careful consideration was given to size and performance.

Also incorporated are slip-fit connections at various strategic points to allow for easy installation and adjustment.

Crucially, the mountune cat-back exhaust is the only exhaust system that will not affect your base vehicle warranty and in addition, comes with a mountune limited lifetime warranty*.


  • Manufactured from AISI 304 2.5” mandrel bent stainless steel tubing
  • TIG welded construction AISI 304 stainless steel hangers
  • Mufflers feature consistent internal diameter 3-layer hybrid synthetic muffler packing effective to 900 degrees C
  • Large 4” rolled edge, polished stainless steel tips with mountune logo
  • Full width rear hanger ensures stable tip location
  • Heavy duty "boss" type clamps
  • CAD engineered and designed
  • Limited lifetime warranty*
  • Does not affect Ford vehicle warranty

Recommended to fit in conjunction with mk3 Focus ST Sports Cat / Downpipe.

Please note: Not compatible with Wagon models. See wagon specific product here.

*Please contact us for warranty terms and conditions.

    Customer Reviews
    4.8 Based on 63 Reviews
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    Filter Reviews:
      Cameron L.
      United Kingdom United Kingdom
      Better than expected

      the delivery was very prompt and only took just over an hour to install with some snagging areas. As other reviews have mentioned, the heat shields do get in the way a fair bit! Otherwise the exhaust sounds great, very sporty and loud when you put your foot down but not at all obnoxious in idle or lower revs!

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      Luke L.
      United Kingdom United Kingdom
      Cat back exhaust

      Awesome bit of kit, so pleased with the look and sound of this exhaust, not overly obnoxious but totally transforms the sound of the car

      mountune Cat Back Exhaust Review
      Chris D.
      United Kingdom United Kingdom
      Can be installed by yourself!

      I installed the item by myself. Jacked the car up and placed it on ramps and axels. Installing the part over the rear suspension was tricky and required moving around some heatshields. My car is a Facelift Focus ST and the stock exhaust used 3 hangers, although the new one had mounts for 4, also matching an unused one near the rear suspension. I also installed a bracket to support the exhaust in the middle after the first muffler. Other than that, this is a great exhaust which is noisy when you put your foot down but doesn't disturb the neighbours when you leave the drive. Best of both worlds. It sounds perfectly tuned with no droning!

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