APR Tuning Products for the Audi B5 - S4

The APR BiPipe Kit eliminates any and all reliability issues of the 2.7T throttle body boot. This cast aluminum pieces features recirculation valve ports that are enlarged, which helps in reducing boost spikes during gearshifts and improves turbo response after the shift. The BiPipe bolts to the throttle body and is sealed by an O-ring. This is the first in a long line of products that APR has developed in-house using our SLA technology.

The APR Boost Gauge utilizes a VDO boost gauge contained in a vent-replacement pod. The pod was designed on the computer with Pro-E for the best in fit and finish and is injection molded in plastic, giving you factory-like look and feel. The gauge itself is a 52mm mechanical VDO gauge giving very accurate and reliable boost and vacuum readings. It reads from 30 in. Hg of vacuum to 25psi of boost. For higher boost systems, a 0-30psi gauge without vacuum reading is available.

APR's Snub Mount Upgrade replaces the front engine mount on the car. This mount enhances upshifting and downshifting, reduces driveline shock, and helps power transfer by taking up excess drivetrain slack.

APR has a stainless steel, mandrel bent, cat-back exhaust for the S4.

APR's S4 Exhaust is a stainless steel, mandrel bent, cat-back exhaust. Our exhaust begins after the two lower factory catalytic converters and is two 2.25" pipes that merge into one 3" pipe. This exhaust is very quiet and simply changes the tone of the exhaust to a deep, unobtrusive sound. With TIG welding, fully stainless construction, and CNC'ed hangers, you will not find a higher quality system on the market.

APR's S4 cat-back exhaust is available with two different sound levels. The Stealth exhaust helps to maintain the S4's subdued character. While louder than stock, it is not too loud to attract attention. The SRT exhaust replaces the center muffler with a special side resonator. This exhaust has a more aggressive sound and a distinctive note.

Highlights of the APR R1 Diverter Valve Include:

* Diaphragm-Based Valve
o High-Temperature, Nomex-Reinforced Material for Extreme Durability
o Zero-Friction
o No Sticky O-Rings to Maintain and Grease
o No Pistons to get Stuck
o Consistent Performance Year Round
* Flow-Optimized, Investment-Cast Main Housing
* Stainless Steel Vacuum Fitting
* Zero-Maintenance Design
* Built with Finest Materials and Surface Treatments
* Fully Machined and Assembled at APR Headquarters in the United States for Optimal Quality Control

The APR R1 diverter valve was designed to be the ultimate solution to the problem of unreliable factory and aftermarket diverter valves and to be the leader in performance. Although most are of good design, factory diverter valves are built in a very conscious manner and the materials and overall life and reliability suffer. For the performance enthusiast, the diverter valve is an important component whose proper operation is paramount to optimal engine operation.

Enter the R1: APR's R1 diverter valve addresses all of the reliability problems of the factory-supplied diverter valves and aftermarket replacements and takes performance to the next level. The R1 is a diaphragm-based valve. A diaphragm is the best option for a diverter valve for several reasons. First off, a diaphragm has negligible friction. Piston-based valves have considerable friction from the piston, o-ring, and bore assembly. The lower friction R1 diaphragm equates to faster response and better overall performance. Secondly, diaphragms do not require the periodic greasing that piston-based valves do. Piston-based valves must be greased periodically (usually every year or sooner), requiring removing the valve from the car, disassembling and reassembling the valve. The APR R1 was designed to be maintenance free for the life of the product. Thirdly, a diaphragm based valve will never have a stuck piston. Piston-based valves periodically incur stuck pistons (especially if the required maintenance schedules are not followed.) Due to the lack of a piston, the APR R1 solves this problem.

The R1 is designed for optimal performance. The main body of the valve is investment cast in an aluminum alloy. By utilizing this casting process in lieu of a more conventional machining process, APR was able to optimize the internal geometry of the valve to provide the ultimate in flow performance. This geometry cannot be created utilizing conventional machining. As such, the APR R1 has much better flow characteristics than other diverter valves. Combined with the low friction diaphragm assembly, this equates to a valve that is truly a performance leader.

The materials used in the R1 are standard setting. The diaphragm is created out of high temperature material and incorporates a Nomex fabric reinforcement layer for enhanced durability and a diaphragm that will never tear. The alloy main body is finish machined at APR and receives a multilayer corrosion resistant and cosmetic enhancing finish. All machining and final assembly takes place at APR headquarters in the United States for optimal quality control and consistency.

Improved cooling leads to smoother and a more consistent power delivery. The APR intercooler upgrade for the S4 is a combination of RS-4 intercoolers and APR designed and developed peripheral parts. The RS-4 intercoolers provide cooling superior to that of the stock S4 intercoolers. Besides being larger, they offer better build quality utilizing aluminum end tanks that are welded to the radiator cores. However, the highlight of the kit is the APR custom designed silicon hoses.

Unrivaled Fit and Finish

The hoses included in the kit are true custom hoses. They are not a combination of off-the-shelf or modified parts. Instead, they are specifically designed for optimized flow by minimizing straight sections and maintaining a maximum radius throughout. These are true one-piece silicon hoses made from our own tooling created in house. These hoses, along with the RS-4 cores, insure the most thoroughly developed intercooler upgrade option on the market. You won�t find this level of refinement in any other kit.

The Kit

The kit consists of two primary parts: one, the intercoolers themselves, and two, the hose kit and associated hardware. The hose kit is made up of two turbo to intercooler hoses, two intercooler to bi-pipe hoses, eight clamps, the horn re-location bracket, and cap screws and lock nuts. This hose kit is available separately.

Power, Drivability, Reliability: these three words sum up our Audi 2.7T K04 Stage III kit. APR's unique approach to product development brings together a product with the level of refinement that this car deserves.

APR has a history of developing high-quality turbocharger upgrade kits. Our 2.7T Stage III upgrade system continues this tradition. This product uses RS4 components, APR-designed components, and of course, APR-engineered engine management software calibrations.

This ultimate turbo system upgrade is now available for the 2.7T cars. This kit is capable of 447 horsepower and 467 foot-pounds of torque at the flywheel on 93 octane gas, while retaining stock-like drivability. The highlights of the kit include the following:

* RS4 KO4 Turbochargers
* RS4 MAF and Airbox
* RS4 MAF to Turbo Inlet Plumbing and Y-Pipe
* RS4 High Flow Fuel Injectors and Fuel Pump
* All Associate Plumbing and Hardware

Show your APR pride with our APR Tuned badges. Our badges have a polished chrome finish to keep a factory-like look over the years. The badge is approximately 2 3/4" long and 1 1/2" tall, and nicely replaces the stock engine designation badge on the back of the car.

APR/Brembo braking systems are engineered for your specific Audi model. Brembo is the world leader in engineering, development and production of high performance braking systems and components. Brembo makes performance braking systems that exceed the demands of today's technically advanced Audi.

Equally important is Brembo’s total committment to manufacturing and quality assurance. To guarantee quality and performance, Brembo controls every step of the process, forging rotors and calipers in their own foundries, manufacturing components to the highest standards in the industry and testing each component as many as 500,000 cycles.

APR/Brembo brake’s level of technology and performance is unrivaled by any other product on the market. By utilizing larger calipers and discs, thermal capacity and brake torque is
increased. This potent combination offers the extreme in Brembo’s leading edge technology for high performance street or track use applications.

APR/Brembo brake systems are fully compatible with the stock ABS and ESP control systems. All of the necessary hardware is included to insure seamless installation.

APR stainless steel, mandrel bent, cat and downpipe replacement for the S4 is $1499.

APR's S4 Cat and Downpipe Exhaust replaces the the exhaust from the turbochargers to behind the lower factory catalytic converters. The system removes the factory pre-cats right off of the turbocharger and includes six separate components. Included are the two pipes off of each turbocharger, a set of pipes with catalytic converters, and a set of test pipes without cats. With TIG welding, fully stainless construction, and CNC'ed hangers, you will not find a higher quality system on the market.