As we explored in our ECU upgrade of Project A4 Avant, there is a veritable plethora of choices a 1.8T owner can make in quest for power. With an upgraded ECU, a freer-flowing exhaust can make a magnified improvement to power levels. There is no question that numbers can be gained, albeit typically much more conservative gains, than an ECU upgrade by itself, but the question remains “at what cost?” both economically and ergonomically.
When considering a new exhaust, one of the most important questions for street-going cars is how aggressive you want to go. Exhausts on the market can range from loud and obnoxious to those with a barely noticeable difference and differ just about as broadly in their adherence to their DOT legality. While one can draw a direct correlation between freer flow and power gains, you also have to remember that the less restrictive the system, the less likely it is to be either quiet or legal.
Since our A4 is primarily for on-road familial use, quietness and refinement are preferred. However, a week in a new German-market S4 sedan proved to us just how quiet our 1.8T was and left us yearning for something more aggressive, but without the typical droning of most aftermarket systems.
Enter Audi Accessories. When we contacted Robert Gal, the man behind Audi of America’s accessories division, he mentioned to us a new stainless cat-back (cat-back = portion of the exhaust system after the catalytic converter to the rear muffler) system Audi was developing for the A4.
Robert explained that the new systems were developed for quattro-equipped A4s only. While units for the 3.0 V6 cars raise the tubing diameter from 2” to 2.38”, our 1.8T system went from 2” in the front pipe and 1.78” at the rear muffler inlet pipes up to 2.25” overall diameter throughout the system.
A prototype system that had been used for fitment purposes was immediately shipped to us to try out on Project A4 Avant. Considering the way our exhaust was packaged in two large boxes and delivered at the front door of our offices like some macabre birthday gift, we suggest you take delivery at the dealer as most sane people naturally would.
Opening the boxes, we were greeted by one visually attractive exhaust, entirely polished to a mirror-like finish. Made of T304 stainless steel with matching 3.5-inch exhaust tips, the system itself appears as much a work of art as a functional upgrade. Tubes of the exhaust are mandrel-bent and tubing indentations found on the original OE exhaust have been eliminated for even less restricted exhaust flow.
For those environmentally concerned owners, Audi claims they’ve developed this system to be fully emission compliant; not altering vehicle gas emission levels from those it had when it left the factory.
In regards to sound, Audi and their supplier worked hard to create a more aggressive tone while still complying with California’s exhaust sound level regulations.
Having been delivered as a three-piece system, installation and assembly was critical. The Audi exhaust upgrade utilizes two flanged connections to ensure a leak-tight seal. Audi suggests that they avoided using the flanged connections as their use on stainless steel systems can prove difficult to seal. No cutting or welding is required to install the exhaust and our exhaust arrived with all gaskets, hardware and instructions. Additionally, all of the car’s original mounting hangers are reused, making installation of the system a relatively easy bolt-on process.
Once the exhaust installation was completed, we fired it up. As exhaust upgrades go, the sound is fairly conservative. At Altered Atmospheres, where the car was dynoed, their employees, who all owned heavily modified cars, thought the sound was too conservative. Contrarily, the staff spouse who drives the car regularly thinks it is a bit too loud. In the end, our conservative tastes with this car left us happy, though we’ll admit the sound is more aggressive than we’d thought it would be.
At low revs on local roads, the car does have a slight drone. It’s nowhere near as bad as other systems we’ve driven, but there is a slight drone at a small range or rpm low in the curve when the engine is heavily torqued. As our car is an Avant, we believe the sound would be less aggressive in the form of a sedan and we plan to drop a layer of Dynamat sound-deadening material in the space underneath the Avant’s trunk floor and we’ll report on its effect once we do.
For the record, we dynoed Project A4 with and without the exhaust on the same day as our ECU dyno session, within hours of each other in the hopes of maintaining consistent external factors such as air pressure and temperature. You will note Dyno Run I and Dyno Run II as identical to those we published two weeks ago. Those two runs represent our APR ECU running in Stock Mode and 93 Octane Mode with the stock exhaust. Dyno Runs III and IV represent Stock Mode and 93 Octane Mode with the Audi exhaust upgrade.
The dyno charts show just how much an exhaust can compliment and amplify the results from an ECU upgrade. In Stock Mode, our car picked up 3.1 peak horsepower and 2.1 lbs.-ft. peak torque. Change the car to 93 Octane Stage I mode and power levels are magnified with a jump of only 1.8hp, but a generous and noticeable 13.3 lbs.-ft. peak torque. Our A4 has even more pull at lower revs, where most of that gain is realized, bestowing the car with plenty of power on demand and minimizing the need to shift.
Reading the Dyno Chart:
Dyno Run .001 – Stage I plus, 93 Octane Program, Stock Exhaust
Dyno Run .002 – Stock ECU Mode, Stock Exhaust
Dyno Run .003 – Stage I plus, 93 Octane Program, Audi Accessories Stainless Exhaust
Dyno Run .004 – Stock ECU Mode, Audi Accessories Stainless Exhaust
All-in-all, we’ve been pleased with the outcome of our exhaust installation. The power increases were noticeable, and the more impressive sound and look of the system adds an air of aggressiveness to the A4 that we’re happy to see. The exhaust note is pleasing, though there’s simply just no way to get a 1.8T to sound as satisfying as our recent short-term V8-powered S4.
The only real problem with the exhaust – a slightly ill-positioned hanger that inevitably pulls the system against the car’s driveshaft resulting in loud and annoying noises – we’re told is a side-effect of our particular exhaust being an early fitment prototype. We’re assured by Audi’s supplier that systems coming out of their factory will not have that problem.
As you read this, Audi should be receiving stock on the new exhaust. When the advertisement featuring the system initially printed in European Car magazine last September, there was no stock on hand to ship to interested parties. We’re told that status is about to change.
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