VW Golf / GTI (MKVII)/ Passat (B8) FWD 1.8T/2.0T Gen 3 APR Cast Downpipe Exhaust System
APR is pleased to present the ultimate Cast Downpipe Exhaust System!
Upgrading the restrictive factory downpipe with the APR Cast Downpipe Exhaust System is a great way to increase performance and add a sophisticated growl to the exhaust note. Ideal performance is achieved through expelling exhaust gasses at maximum velocity through APR’s proprietary, low-turbulence, investment cast downpipe. Designed and assembled in-house, the system utilizes only premium materials and world-class manufacturing techniques to deliver unmatched quality and reliability.
- Designed and assembled in-house.
- T304L stainless steel construction.
- Argon back-purged TIG welding.
- Investment cast downpipe.
- 77mm inlet with integrated flange.
- Low profile, sealed/corrugated flex section.
- 76mm outlet with integrated bracket.
- 8mm billet bracket.
- 76mm brushed and de-burred piping.
- Non-swedged/slip-fit/flanged piping.
- Investment cast o2 bung.
- 300 cell, 100mm x 100mm GESI catalyst.
- OEM-style slip-on clamps.
- Reducer for OEM catback compatibility.
- APR Stage II ECU Upgrade price waived.
- Limited lifetime warranty.
The factory downpipe system consists of smaller, 63mm piping with varying bends and multiple restrictive high-cell-count catalysts, all of which contribute to a less than ideal flow path and hindered performance. APR’s engineers took a multi-step approach to maximizing flow, reducing under hood temperature, and eliminating unnecessary restrictions all in a unique package only APR can deliver.
Detailed component information
The APR Cast Downpipe Exhaust System is a complex system designed to deliver maximum performance. Each component was designed and developed with the absolute best in performance, strength, reliability and quality in mind.
Cast Downpipe Inlet and Outlet
The exhaust system features a strong, investment cast, T304L inlet and outlet designed to maximize flow and minimize turbulence. By casting the inlet, APR’s engineers were able to create a smooth and high-flow exhaust path that maximized flow through swept blends and shapes that are otherwise not possible through conventional fabrication techniques. The inlet perfectly matches the factory turbocharger’s 77mm outlet and gradually necks down over a long distance to further enhance performance. The mounting flange and bracket are integrated into the casting, and TIG welding at the flex section ensures a clean inner surface eliminating turbulence, vortices and eddies to the highest degree.
With a nominal wall thickness of 2.55mm the downpipe is strong and produces a refined exhaust note compared to thin wall tubing systems. The cast sections undergo a tumbling process to smooth and de-burr any imperfections inside the pipe, while simultaneously enhancing the exterior finish. Lastly, all necessary surfaces are CNC machined for an accurate fit.
APR’s engineers specified a T304L stainless steel, OEM-style flex section that is fully sealed with a corrugated inner lining to improve flow and reliability. The low profile design and minimal use of bradding material eliminates clearance issues common with other designs that can billow, rub, rattle and fray over time.
Designed to stand the test of time, the bracket is CNC machined from 8mm-thick billet T304L stainless steel and the hanger feet are threaded into place, eliminating the need for welds. Weight is removed from the bracket, wherever possible, while not hindering its structural integrity. The bracket attaches to the cast downpipe’s integrated mounting bracket, and CNC machined spacers enable compatibility across multiple vehicles.
The APR Downpipe Exhaust System features premium grade T304L stainless steel for its excellent appearance, strength and corrosion resistance properties. The pipe is rolled to the 76mm European standard diameter with a 1.5mm wall thickness and a seemingly non-existent weld seam.
Pipe is cut to length in-house via APR's CNC-controlled bandsaw to an accuracy of .25mm, ensuring a precise fit. Each pipe is de-burred, and the exterior finish is brushed to give the exhaust piping a clean and attractive appearance worthy of the APR name. APR’s fabrication team uses argon back-purging during the welding process, leaving a clean and smooth interior surface, and TIG welding for strength and appearance. Lastly, no swedging or slip-fitting is necessary due to APR’s OEM-style clamp design, leaving smooth and less turbulent connection points.
APR’s engineers specified a T304L stainless steel, OEM-style exhaust clamp designed to eliminate the need for flanges, swedging, or slip fittings. By using this low profile design, the exhaust system can be positioned higher in the exhaust tunnel and away from the ground with better clearances compared to flanged setups. Each clamp allows for less turbulence and greater accuracy at the connection points as the pipes simply butt up to one another rather than the ambiguity and voids associated with swedged slip fittings. Furthermore, the clamp doesn’t rely on deforming the pipe to provide a tight seal, making install and removal more convenient.
O2 Sensor Bung
APR’s Engineers paid special attention to the details when designing the APR Cast Downpipe Exhaust System all the way down to the oxygen sensor bung. APR’s O2 bungs are investment cast from T304L stainless steel and are curved to perfectly fit on 76mm piping, without protruding into the pipe, as this would further impede airflow beyond the sensor itself. The bungs are TIG welded to the piping and back-purging is used to ensure the interior surface is smooth and clean.
APR’s engineers specified a high-quality and high-flow GESI metal 300-cell catalyst ideal for forced induction application. During dyno testing, the 100mm x 100mm design showed no measurable loss in power, thanks to the catalyst’s specifications.
Internally the catalytic converter features a proprietary blend of precious metals and loading technology that helps to reduce emissions and smell common on cat-less setups. With performance in mind, the catalyst is placed far away from the turbo outlet to reduce turbulence in the downpipe and to help reduce under-hood temperature. The low-profile catalyst features a fully captured substrate brick, which is furnace braised to the outer mantle and physically captured by the diffuser cones preventing rattling, rotation, and damage to the substrate. Subsequently, a byproduct of running the catalyst is a reduction in noise, making the system as a whole more pleasing to the ear.
A simple and removable, T304L stainless steel reducer, featuring a smooth transition, is included, making the APR Cast Downpipe Exhaust System directly compatible with the OEM catback exhaust system. Both 1.8T and 2.0T reducers are included with each system.
Oxygen Sensor Harness
A high quality oxygen sensor extension harness is included as the catalyst and sensor bung is relocated further away from the turbocharger.
The APR Difference
The Engineering and Designing Phase
In the past APR worked with other manufacturers to develop a limited range of private-label exhaust systems outside the scope of APR’s internal development and manufacturing capabilities. Understanding the limits of such a program, combined with APR’s desire to deliver higher-quality products in a timely manner with better customer support, APR invested in internalizing the program. With the release of this exhaust system and the others like it, APR is pleased to present our first systems fully designed and engineered in-house from the ground up!
Design and development begins with the use of APR’s professional grade in-house coordinate measuring machines. APR’s engineers have full access to a Romer Absolute arm with integrated laser scanner, FaroArm and Creaform 3D laser scanner for collection of special constraints surrounding the factory exhaust system. The engineers scan the vehicles and create detailed 3D maps of their design environment while designing each system in PTC Creo 3.0 CAD software.
Using APR’s in-house stereolithography 3D printer, rapid prototypes are created for fitment on the vehicle. The design is easily and quickly verified, and if necessary, changes can be made. Once adequate clearances and fitment is confirmed, especially in areas that move under load, physical quick-cast prototypes are created and fitted for final verification through real-world use.
APR’s world-class manufacturing partners from around the globe are responsible for manufacturing each component that falls outside of APR’s internal capabilities. Working closely with each manufacturer, APR’s engineers supply CAD models, materials specs, and other design specifications and work hand-in-hand with the manufacturer to develop the components. The end result is a collection of components, wholly unique to the APR name, awaiting final finishing, assembly and quality control at APR’s 78,000 square foot facility in Opelika, Alabama in the USA.
The Fabrication, Finishing and Assembly Phase
Manufacturing takes place both internally and externally to APR while finishing and assembly is completed in-house. APR’s fabrication team cuts, brushes and de-burrs premium grade T304L stainless steel piping for use in each midpipe. Then each cast component is sent through the ceramic vibrating tumblers to smooth and de-burr surface imperfections. Each component is then cleaned by hand and prepared for assembly.
APR’s fabrication experts TIG weld each component, creating reliable, high quality and attractive welds. Each component is back-purged with argon during the process ensuring the weld is strong and consistent, as well as clean throughout. With this process complete, the APR Cast Downpipe Exhaust System is born!
Final Quality Control
APR has placed a large emphasis on improving quality control across various product lines, and the exhaust program is not excluded. To ensure the systems are delivered as advertised, APR’s engineers have taken a multi-step approach that encompasses many techniques that go beyond the industry standard.
APR’s engineers request full metallurgy reports with each batch of components to ensure the components are made with the T304L stainless steel grades specified on the original design prints. This information is then cross-referenced against randomly selected and independently tested samples before the components are released for assembly.
Great designs only matter if the manufacturer delivers the components as expected. To help ensure the designs are as specified, APR’s engineers randomly select components and conduct full dimensional inspections using in-house 3D laser scanning equipment. Tolerances are digitally checked against the original specifications and passed or failed based on the results.
Operating in an environment designed for accuracy and repeatability, APR’s fabrication experts leave little room for error during the final assembly phase. Jigs and fixtures, created in-house, live on custom-specified fabrication tables featuring repeatable indexing holes and extremely flat surfaces. This working environment ensures the highest level of quality control during the assembly process and safeguards against dimensional variations potentially created during the manufacturing process. The end result is a system that fits every time as it’s true to the original design specifications.
When hand-building the products in-house, an extra level of control takes place. Components are visually checked for imperfections, and items that fall out of quality standards are rejected. The products are then packaged with care before being distributed across the world.
APR’s confidence in the system’s quality allows for a limited lifetime warranty.
Attention International Buyers! We cannot ship APR products internationally. We are authorized to ship products within the United States Only.
APR LLC is an automotive engineering firm operating a 36,000 sq. ft. performance campus in Opelika, AL. APR was founded in 1997 with a corporate philosophy of Integrity, Excellence and Innovation. APR's Sole Mission is to provide the highest quality and most highly engineered aftermarket performance products available for Porsche, Audi and Volkswagen vehicles.
APR, Enhancing the Driving Experience with No Compromise.
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