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.
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.
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.
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 80mm outlet and gradually necks down over a long distance to further enhance performance. The mounting flange, oxygen sensor bung 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 T304 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 T304 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 T304 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.
Our system uses OEM-style low-profile slip clamps 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.
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 bungs. APR’s O2 bungs are investment cast from T304 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. Lastly, a billet T304 stainless steel bung plug is included to cap off extra ports not needed on some models.
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 brazed 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, T304 stainless steel reducer, featuring a smooth transition, is included, making the APR Cast Downpipe Exhaust System directly compatible with the OEM catback exhaust system.
Included with each system is an OEM gasket, designed to mate between the downpipe and the turbocharger.
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.
Application GuideVehicleEngine*TransmissionDrivetrainPart NumberPrice *EA113 and EA888 Gen 1 & 2 only. Does not fit EA888 Gen 3 engines with integrated v-band turbo.