APR Downpipe Kit, For MK2 TTRS

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 gases 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, 63"m 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.

Quick Facts

Designed and assembled in-house.

T3"4L stainless steel construction.

Argon back-purged TIG welding.

Investment cast downpipe.

80mm inlet with integrated o2 bung and 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 bungs with billet plugs.

3"0 cell, 100mm x 100mm GESI catalyst.

OEM-style slip-on clamps.

Low-profile, broadband noise cancellation resonator.

Reducer for OEM catback compatibility.

OEM gasket.

APR'stage II ECU Upgrade price waived.

Limited lifetime warranty.

The factory downpipe'system consists of smaller, 63"m 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.

Cast Downpipe Inlet and Outlet

The exhaust system features a strong, investment cast, T3"4L 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 2.5"mm 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.

Flex Section

APR's engineers specified a T3"4L 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.

Bracket

Designed to stand the test of time, the bracket is CNC machined from 8mm-thick billet T3"4L 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.

Midpipe

The APR Downpipe Exhaust System features premium grade T3"4L 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. CNC mandrel bending is used to ensure a continuous diameter throughout the design. Lastly, no swedging or slip-fitting is necessary due to APR's OEM-style clamp design, leaving smooth and less turbulent connection points.

Please Note: TT/TT-S model excludes the broadband resonator and CNC bend.

Clamps

APR's engineers specified a T3"4L 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.

Bungs

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 T3"4L 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 T3"4L stainless steel bung plug is included to cap off extra ports not needed on some models.

Catalyst

APR's engineers specified a high-quality and high-flow GESI metal 3"0-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.

Resonator

A broadband noise cancellation resonator is used to reduce the volume of the exhaust note. The low profile T3"4L stainless steel cylinder features a straight perforated tube, wrapped in T3"long-strand stainless steel fiber followed by a tightly woven fiberglass outer wrap. The straight-through design keeps exhaust velocity high, and turbulence low maximizing performance. A brushed finish is applied to the exterior to give the resonator an attractive appearance.

Reducer

A simple and removable, T3"4L stainless steel reducer, featuring a smooth transition, is included, making the APR Cast Downpipe Exhaust System directly compatible with the OEM catback exhaust system.

Gasket

Included with each system is an OEM gasket, designed to mate between the downpipe and the turbocharger.