GMG is proud to introduce the World Challenge Sport exhaust system for the 2010+ Audi S4 and S5 3.0 Super Charged engines. Designed after our proven World Challenge RS4 system, the World Challenge (WC) system incorporates mandrel bent T304 Stainless steel construction throughout, our proprietary cross over center section which improves performance and sound, while reducing overall weight.

Our system features two mirror polished sport mufflers which are stainless throughout their construction (including the packing) and finished with dual 3.5" RS style tips. ( quad tips available as optional) Our system is a true bolt on cat back system which retains the factory clamps to ensure no exhaust leaks at any of the joints.

The GMG World Challenge sport exhaust systems offers S4 and S5 V6 owners a "tuned" sound without interior cabin drone. Designed for the sophisticated S4/S5 owner who wants to wake up the sound without compromising the everyday drivability.

• Constructed from T304 Stainless Steel
• Mirror polished sport mufflers
• Proprietary crossover center section
• Dual 3.5" RS Style tips or Quad 3.5" tips optional
• Uses Factory clamps to ensure no exhaust leaks

Stock Cat

GMG introduces the World Challenge ( WC) header system for the B8 S4.

Designed and engineered in house at GMG, our 3 into 1 tubular header with F1 style merge collector is a direct replacement header system which incorporates a German made 200 cell metal matrix sport catalyst ( NO CEL). The system utilizes highest grade U.S. made T304 stainless tubing that is purge tig welded and normalized for strength. Additionally, the system features stainless steel CNC machined flanges throughout as well as CNC machined stainless steel 02 sensor bungs.

This system is a direct replacement system and bolts up to stock downpipes or optional GMG downpipe and GMG WC cat back sport exhaust system.

All systems are hand built to order.

The GMG crank pulley is made of high strength light weight alloy's. The reason for this is to introduce a slightly lighter overall crank pulley. The Harmonics of the stock pulley have been tested and stored into our data base. The frequency spectrum of the blower at all speeds has also been acquired, then through dynamic modeling and testing on a Spintron machine. We were then able to determine the ideal material choice for construction, damping media, and harmonic spectrum, for the desired operating range and environmental conditions of its intended use.

Fully engineered damping frequency of the GMG crank pulley will reduce the harmonics produced by the increase in blower speed. This is the most overlooked scenario when looking to increase blower speed to produce more boost. A solid blower pulley will transmit any and all changes of the blower harmonics to the crankshaft. The factory crank pulley is engineered to work at stock blower speeds and boost.

The GMG crank pulley has the increased blower speed and frequency changes, factored in to the design.

With the current trend of manufactures looking to keep profits high, The days of well over engineered components are long gone, Every manufacture now only builds their cars to deliver reliable performance when used in the "as delivered configuration" (Stock). This makes it even more important to understand when engineering a performance product for today's performance cars.

As boost and blower speed increase, counter torque on the drive belt also increases (the force needed to drive blower) By increasing the diameter of the drive section of the crank, the force on the belt is decreased, there by reducing belt slippage, wear, and reducing the belt whip that is produced when sudden changes in engine speed occur :IE down shifting, wheel spin, exct... we know this because the force needed to drive the blower at any given boost pressure and speed, will be the same regardless of what method is used to produce that speed and boost. Knowing this as the surface area decreases ( smaller blower drive ) the pressure on the belt has to increase, the opposite is true for increasing the crank drive of the blower, the pressure will go down because the surface are has gone up.

PSI = force / area (pounds / square inch) example 100 lbs of Force / 5 square inches = 20 psi, but if the area were to be increased to 10 square inches, (100 / 10) now PSI = 10, so the pressure on the belt ribs would go down.

Only the supercharger drive ratio is altered to achieve the max safe boost of blower, all other drive ratios are unaffected and driven by the inner drive ring of the crank pulley.

Ease of installation, because the crank pulley is bolted on to the pressed hub of the crank shaft, there is no need for a special tool or a puller. Also there is no need to heat or specially align any parts of the drive. There is also no evidence of tampering or modification to the engine as the GMG Crank pulley replaces the stock one exactly.

GMG WC Sport lowering springs- Made by Eibach for GMG to our specifications ( these are not stock springs that have been re-powder coated like most other tuners) Stepless pitch design, truly progressive rate designed to work with the active suspension in the S4.

The springs feature a 1.3" drop from factory with exceptional ride quality and handling without any compromise.

GMG is proud to introduce the World Challenge sway bar kit for Audi S4 models. Our WC - S4 Sway bar kit for the S4 is the most sophisticated kit on the market today offering the most rigidity of any bar on the market today. Designed to work GMG's WC Sport lowering spring kit or any aftermarket suspension kit such as KW, Ohlins or Moton as a direct replacement sway bar set. Our sway set utilizes stock sway bar mounts for smooth and quiet operation in all settings while minimizing body roll on the street and on the track. The optimum handling and chassis response in the corners.

• Manufactured by Eibach to GMG specifications.
• Designed and built as a matched set front and rear for optimum handling and tuning.
• Made of the highest quality and strength tubular steel tubing.
• 2 way front and rear adjustability
• Features high performance urethane bushings front and rear.

*Sway bar FAQ: Sway bar rigidity or stiffness is not determined by sway bar thickness alone. Grade of material (tensile strength of steel) and design of sway bar are more important then the overall diameter.