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Unitronic Cat-Back Exhaust System for B8/B8.5 Audi S4/S5
CAD $ 2,989.99


Unitronic is pleased to present its 2.5” Cat-Back Exhaust System for the B8/B8.5 S4 and S5. Featuring TIG welded T304 Stainless Steel CNC mandrel bent construction, T316 stainless steel flanges, and a straight-through, free flowing design; Unitronic’s Cat-Back Exhaust Systems are designed to remove the factory exhaust restrictions to unleash the full potential of the engine. 

Like all of Unitronic’s Performance Exhaust Systems, a unique v-band fastener system, using T316 Stainless Steel flanges was utilized to ensure a leak proof connection every time. This is achieved through a locking ring on all Unitronic v-band flanges to guarantee a centric alignment of the two flanges. Unitronic’s Cat-Back Exhaust System features a high density, high temperature glass fiber muffler packing, and engraved Unitronic logo. These attributes combined ensure maximum performance, while maintaining a comfortable and unobtrusive tone inside the cabin. Exiting at the rear, exhaust gasses pass through dual 3” slash cut tips and engraved with the Unitronic logo.

  • Dual 2.5-inch T304 stainless steel:
    Top quality material that will not rust and will outlast your vehicle.
  • T316 stainless steel flanges:
    Durable, rust proof and laser cut.
  • Brushed finish matte finish:
    Brushed matte finish for the best possible look.
  • 4-inch Corrugated stainless steel flex section: 
    High quality flex with interlock construction that will stay leak proof for years; allows engine movement without stressing the factory rubber mounts
  • Polished 3-inch Double walled exhaust tips:
    Mirror polished tips with engraved Unitronic Logo.
  • Flow-match transitions:
    Flow-matched transitionsfor maximum performance and airflow.
  • Integrated X pipe:
    Reduce unwanted sound frequency; unique exhaust tone.
  • Sound absorption technology:
    Perforated chamber packed with high quality and durable high temperature fiberglass wool; ensures a deep tone while absorbing unwanted frequency.
  • Sound Reflection:
    : Sound reflection chamber used to cancel drone noise and to ensure comfortable sound level in the cabin.
  • Straight-through, free flowing muffler design: 
    Optimal performance achieved by removing restriction and reducing back pressure.
  • TIG welded construction: 
    Professionally TIG welded to ensure longevity, durability and top tier craftsmanship.
  • Unique v-band fastening system featuring Clampco® clamps: 
    Maintain a perfect alignment of v-band flanges while ensuring a leak-proof connection every time. Fully reusable and quick to install.

Hardware Included

  • Unitronic Left Downpipe Section
  • Unitronic Right Downpipe Section
  • Unitronic Front Resonator Section
  • Unitronic Mid Resonator Section
  • Unitronic Left Rear Muffler
  • Unitronic Right Rear Muffler
  • All Necessary Hardware Included

Recommended Software

  • Stage 1
  • Stage 1+
  • Stage 2+



This product may not fit all the vehicles listed. Please make sure it is the right part for your application or contact us for more information.

Application Guide

Unitronic Cat-Back Exhaust System for B8/B8.5 Audi S4/S5

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Brand : Unitronic
MFG Part # : UH011-EXA
SEM Part # : UH011-EXA
Price : CAD $ 2,989.99

SEM Motorsports Ltd

SEM Motorsports Ltd is a full service German automotive maintenance facility located in Toronto Ontario.

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