2005.5-on B7 S4 Dual Catback Exhaust

Now the first catback available in North America for the 2005.5-on B7 Audi S4. Killer performance like our B6 system below but with new aggressive quad tip outlet design. Fully stainless heavy gauge solid stainless tips all hand polished. Tips are tapered in length to follow the contour of your S4 bumper. Rear mufflers have two full pipes internally (no cheap single internal pipe with ugly external Y-pipe for tips) This system will fit your S4 like a glove and may be combined with our super powerful downpipes and cats for the ultimate in power and sound. Non-resonated (no inline center mufflers) is shown below. You can order yours today below on this page.

2004-2005 B6 S4 Dual Catback Exhaust

The first and original catback exhaust for the new S4 V8 4.2, Milltek Sport. We all know that the stock exhaust is far too quiet and restrictive. Tuners in Europe have reported gains of 15hp (at the wheels) with this catback exhaust and that has been verified in the USA on a 4-Wheel Dynapack dyno along with a 20 lb-ft gain in torque (at the wheels). Awesome Milltek quality and fit, Dual 100mm tips. Get that deeper sound with the power to match. New non-resonated system available. Eliminates the two center mufflers for a louder sportier sound. Power equal to the resonated version but with a more aggressive attitude (not pictured). Milltek gives YOU the choice for your V8 S4.

NEW SOUND CLIP. CLICK HERE AND CRANK IT UP (Manifold-back resonated)

Milltek V8 4.2 S4 Downpipes and Cats (2004-on, B6 and B7)

Milltek is out in front again with the impressive downpipes and cats for the new 4.2 V8 S4. Bolts-in directly to your exhaust manifolds. Replaces your OEM primary cat with a 200-cell platinum-coated metal high-flow cat and eliminates your OEM secondary cat. Power gains come when you can free up flow as close to the engine as possible and Milltek delivers. Dyno proven to deliver 20 lb-ft and 15hp at the wheels. When combined with the Milltek catback your S4 jumps by 40 lb-ft and 30hp at the wheels. More torque, more power, more growl. An unbeatable combination for the spectacular 4.2 V8 S4 from Milltek and Stratmosphere. TipTronic now available!

Some technical details about the German catalysts in these phenomenal systems:

These catalysts are made from special stainless steel containing aluminum (called ‘Fecralloy’). This material was developed in England in the 1970’s specifically to provide resistance to oxidation at very high temperatures. The material is used as a very thin strip (2 thousandths of an inch) and is coiled together to make a honeycomb structure. Because the metal strip is so thin, the honeycomb has a very low flow-obstruction. To reduce the flow-obstruction even further, the honeycomb is made with 200 ‘cells’ (i.e. channels) per square inch (compared with 400 per square inch for a standard catalyst). The result is that about 85% of the total cross-section is open. The honeycomb is held together by using a special nickel-based brazing material which is applied in a vacuum. The finished honeycomb is then coated with Aluminum Oxide, some rare earth metals and Platinum and Rhodium. The Platinum and Rhodium are applied at a rate of 25 grams per cubic foot, which compares with between 5 and 10 grams per cubic foot for typical US aftermarket items. It is normal practice in Europe to use much higher quantities of precious metals on catalysts, because European gasoline has more impurities in it which gradually poison catalysts. If catalysts with such high levels of precious metals are used with US fuels, the  post-catalyst emissions are extremely low and the durability of the catalysts is very good indeed.

One other good point about using catalysts made of metal foil is that they are better at coping with localized overheating than ceramic cats. The metal conducts heat better than ceramic materials, so localized ‘hot-spots’ are avoided. This means that any melting of the catalyst is extremely unlikely, even if it is exposed to rich mixtures as a result of wild cams or modified engine management systems.