For Audi enthusiasts

05s4 exhaust photo



16 December 2010

Driving the Audi S4 around docilely throughout the day-to-day commute, it’s easy to forget that the car’s 3.0-liter V6 is supercharged. You have to listen with the audible tenacity of a recording engineer in order to say you hear any sort of whine from the Eaton supercharger unit underneath the hood and even then you’re more than likely a victim of wishful thinking or maybe simply bullshitting. There’s a reason Audi is again on the Ward’s 10 Best Engines list with the 3.0T FSI and this can be very readily attributed to the V6 mill’s performance, efficiency and most definitely its refinement.

There’s no doubt that the engine’s mix of these three qualities is the reason that it is very quickly replacing the brand’s venerable 4.2 V8 not just in the S4, but now also in the A6 and Q7… and don’t be surprised if it does the same in the A8 before all is said and done.

Audi’s shift toward downsizing with the 3.0T looks to be nearly an entirely winning move in nearly every aspect… except maybe for those who want sound. Okay, so the 3.0T FSI will never sing as melodically as the 4.2 V8 but we all know V6s can be made to have an intimidating bark. The 3.0T, even in its sportiest S4 application as experienced with our 4 Season test car, is surprisingly quiet. A6 and Q7 owners likely welcome this feature, especially the ones who just traded in some sort of Lexus, but S4 owners are a different lot and they want some noise.

Those S4 owners aren’t alone. A number of Audi staff we’ve spoken to at Audi agree. In fact, we hear Audi may be working on some sort of sportier exhaust option for future 3.0T equipped models but current S4 owners looking for a solution will have to look toward the aftermarket. Fortunately, there’s no shortage of companies with product for the hot-selling Audi S4.

There’s a trick to the aftermarket though. It pays to do your research. Ask around in online forums or, better yet, go listen to systems for yourself at an Audi Club meet or a four-ringer attended cars and coffee gathering. Just how much volume you seek varies from driver to driver though most everyone will agree you’ll want to steer clear of drone. The latter will likely leave you dreading that commute in your high performance Audi… that same commute you once eagerly awaited.

Choosing an Exhaust
If you’re anything like us then you prefer refinement in your performance. Yes, we wanted more volume but not so much that we’d wake the neighbors or look like a wannabe rally star in a coffee-canned Lancer. Given our preferences, our interest was immediately drawn to Alabama’s APR and their cat-back stainless steel system utilizing Reflective Sound Cancellation (RSC) technology.

APR boasts their RSC design is technology used by NASA and the idea behind it is certainly intriguing. Mufflers in the system go sans baffles with a specially designed muffler interior designed to cancel out sound resonance. The idea is that you get maximum exhaust flow and impressive silencing of the engine, which are two characteristics that rarely go together when talking about exhausts.

Further upstream of the RSC exhausts is an X-pipe that allows gases coming down through the system to retain their inertia. The idea is to keep the flow going as efficiently as possible and the payoff is power. To that end APR reports a gain of 17 hp and 15 ft-lbs of torque after installation of the system.

Arrival and Installation
The RSC exhaust comes shipped in a thorough and relatively compact package. The entire system breaks down into its many components (shown), including directions and all the necessary pieces you’ll need. We’ve become quite accustomed to APR’s thoroughness in this arena.

You’ll likely want to use a lift for such an installation so we headed over to APTuning in Lebanon, Pennsylvania. APTuning is the local dealer for APR and does these installs all the time so the choice was a natural one. Installation is relatively straightforward and simple and the hardest part of the install will likely be figuring out how to cart home your giant Y-shaped stock exhaust if you wish to retain it and not cut it up.

On the car, the system looks subtle. The S-car’s quad round exhaust tips are retained and they come either in high-polished silver or diamond black with APR logos etched on the top. If you’d rather go stealth and logo-less it appears that you can flip the tips upside down and switch sides, pointing the blank sides toward the sky. Do that and most might assume you’re running a “stock-ish” system.

When we first started our S4 following the installation and revved the engine we were quite surprised by the quietness. Sitting in the driver’s seat in APTuning’s parking lot we barely noticed a difference from stock. It’s not just that we were surprised by the refinement, we started to wonder if there was an audible point to doing the install. On the drive home and driving since then, we’ve realized there was definitely reason.

Having never owned an RSC system before, we went into our ownership experience of the on a steep learning curve. We’ve realized there are many upsides and just a few downsides. We’re positive the upsides make it well worth it and want to share what we’ve learned to best inform you of what we’ve seen.

In the driver’s seat, you notice the improved sound under load and at full throttle. It’s noticeably meaner for front seat passengers but not brutally so. What’s so interesting about RSC though is how it focuses that engine sound. Sit in the back seat of the car and the change in the growl seems more intense than you might experience from another exhaust. Stand outside the car as it throttles past or away from you and the experience is even more impressive. The sound isn’t annoying or boy racer. Instead it adds that level of volume and voice of anger to the car’s note that you would likely come to expect and demand.

To someone operating the driver’s seat dyno the car feels faster though this is always intensified by the welcome change in note. 17 hp of gain on a 333 hp engine is only about 5%. More noticeable performance gains are to be expected from modifications like a tuned ECU, modifications with which this exhaust will make an excellent pairing.

We’ve heard droneless exhaust tuning for S-tronic cars is much harder than it is for cars with a 6-speed manual. Fortunately that plays to our favor since our car has the stick. In as much we are extremely pleased to report that we’ve experienced no audible drone. This thrilled us. We’ve not yet had a chance to sample an S-tronic S4 fitted with the exhaust.

So is there a downside? We’re not exactly sure but we suspect there is one side effect that’s been a bit of a nuisance. Shortly after we installed the car we began to notice some buzzing rattles at very short rpm ranges. First it was the spring-loaded cover to the rear power outlet, and then we noticed something in the passenger door.

Are these buzzes related to the exhaust? Well, the car didn’t buzz before and little more than 12,000 miles had been logged on our S4 prior to installation. The nature of the technology utilized has us wondering. All of that sound is redirected somewhere and we suspect there is a harmonic resonance from the exhaust that is causing these buzzes. Short of hiring a sound engineer or swapping back the factory exhaust, we’re not exactly sure how to prove a correlation. The buzzing is a nuisance but it’s not intense and it happens on such a short range of rpm so we’ve very easily learned to live with it. It’s been such a minor side effect but we felt it worth mentioning.

APR’s RSC exhaust system for a B8 Audi S4 like ours sells for $2,339.00 though we’d suggest owners of Titanium Package cars similar to our car with Audi Exclusive Black Optics should consider spending slightly more for the setup with Diamond Black exhaust tips at $2,469.00. Either way, we doubt this exhaust will disappoint. We’re looking forward to pairing it to APR’s recently released ECU upgrade in order to unlock even more power.


4 Season 2010 Audi S4 Index Page
APR RSC Exhaust for B8 Audi S4 at

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