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The IE B9 A4 & A5 Catted Downpipe is engineered to completely reduce turbocharger back pressure and increase turbo spool required for the calibrations of a stage 2 ECU tune. The combination of a performance downpipe and ECU tune together unlocks the full performance potential of your stock turbocharger and engine, delivering 97 horsepower over stock. Get ready to experience addictive power gains across the entire RPM range and an aggressive exhaust growl you are bound to love.

All IE exhaust systems are designed in-house using state of the art digital scanning for a perfect fit and manufactured from thick wall 304 stainless steel offering a lifetime of performance and fun.




  • Excellent horsepower gains - with matching Stage 2 Tune
  • Cast sections ensure maximum flow and gorgeous fit and finish
  • True 76mm Throughout- Does not neck down to OE Sizing at catalyst discharge
  • Direct bolt-on fitment - no modification or bending of mount brackets required
  • 100% 304 stainless steel pipe construction - lifetime of worry free performance  
  • Thick cast turbo flange - ensures long gasket life and no leaks
  • High flow 200 cell catalytic converter - full power with reduced pollution
  • High quality metal matrix catalyst flows more than cheaper ceramic matrix cats
  • Tuned resonator - keeps highway drone to a minimum
  • Fully lined extra tough flex section will never collapse internally
  • Complete Kit - includes all mounting hardware (nuts, bolts, clamps, gaskets)

Sound Tuning

IE engineers elected to use a resonator in the B9 A4 & A5 exhaust. The result was a much better sounding exhaust overall. The factory cat back has a very unpleasant rasp when used with a downpipe which does not have a resonator. As IE engineers are true enthusiasts as well, it was very important that the exhaust also sounded great. Check out the video to hear stock vs. IE sound clips.

*All sound clips are on a Stage 2 vehicle with IE cold air intake and intercooler installed. Only the downpipe was changed, no modifications were made to the factory installed catback.

High Flow Catalytic Converter

IE’s performance downpipe includes a high-flow 200 cell per inch metal matrix catalyst located as close to the turbo as possible. Metal matrix catalysts are higher performance because the matrix web is thinner, allowing higher flow in the same size. Our catalyst is also a very large diameter, allowing a large flow area and maximum power. By being placed close to the turbo, emissions and unwanted unpleasant smells are greatly reduced.

Integrated Engineering Audi B9 Performance Catted Downpipe (A4 & A5) ML Performance UK

High Flow Cast Sections

Typical aftermarket downpipes use bends or cuts to form the shape of the downpipe; this allows the use of larger piping, but sacrifices flow and often times fitment. Using specialized 3D scanners and software, IE engineers can design odd shapes and sizes to maximize flow and conform into tight spaces without any sacrifices. To accomplish these shapes, sections of the dowpipe are cast manufactured from the digital models. The result is an incredibly high-quality performance unit with a perfect fit and beautiful finish.

Integrated Engineering Audi B9 Performance Catted Downpipe (A4 & A5) ML Performance UK

Consumer Notice

By purchasing a motorsport/racing product ("Product"), you represent that you understand and agree that: the product is not designed to meet any applicable emissions standards, whether in the USA or otherwise, the product is not C.A.R.B. Compliant, and that the product is not for sale or use in California, USA nor any other jurisdiction where the sale or use is prohibited by law. Integrated Engineering, LLC makes no representations, warranties, or claims that this product complies with any applicable emissions laws and expressly disclaims any and all such representations, warranties, and claims, whether express or implied. By purchasing this product, you represent, warrant, and agree that it is your responsibility to inform yourself of any laws or regulations that may apply to your purchase and/or use of the product.





2016+ (B9)




2016+ (B9)




2017+ (B9)


Manufactured by

Integrated Engineering (IE)

Part Number


Useful Information

  • We deliver to every country in the world, if shipping rates are not available at checkout please contact us.
  • Some item(s) are not actively held in stock and usually sell out quickly, please contact sales to perform a stock check if you are unsure.
  • Full tracking is available for all orders, you will receive tracking and dispatch updates via email.
  • It can take up-to 16 working days for out of stock orders to be dispatched.
For more shipping & delivery information, please click here.
We offer fitting on most of our products at our facility in Warrington, Cheshire. Please contact us to get a quote on have us fit your products.
Ultimate Customs Group LTD do not accept any liability if damage is caused to your car by the installation of this product.

Professional installation is recommended on all of our products. Please contact us to see if we offer a fitting service for the item(s) you wish to purchase.