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APR Cast Downpipe w/Cat (09-13 A3 Quattro, 12-13 Golf R)

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SKU: 107284
MPN: DPK0001

Product Details


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.

Manufacturing Process:


Cast Downpipe Inlet and Outlet:

The exhaust system features a strong, investment cast, T304L inlet and outlet designed to maximized 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.

APR Cast Downpipe (12-13 Golf R) APR Cast Downpipe APR Cast Downpipe


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 Cast Downpipe Inlet APR Cast Downpipe Outlet APR Cast Downpipe Bracket


APR Catpipe/Midpipe with catalyst and resonator APR Catpipe/Midpipe with catalyst and resonator

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. 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.

Catalytic Converter:

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.

APR Catalytic Converter APR Catalytic Converter Installed



APR Cast Downpipe Resonator APR Cast Downpipe Resonator Cutaway

A broadband noise cancellation resonator is used to reduce the volume of the exhaust note. The low profile T304L 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.



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.

APR Cast Downpipe Reducer


Downpipe Includes:

  • Downpipe
  • Bracket
  • Clamps
  • 02 Bungs
  • Catalytic Converter
  • Reducer
  • Gasket

Stage II ECU Upgrade Information

For the best results, APR recommends installing the Stage II ECU Upgrade. This upgrade requires purchase of an APR Stage I ECU Upgrade, and is included for free to the original owner and original vehicle with the purchase of an APR Cast Downpipe Exhaust System!

Product Features

  • APR Stage II ECU Upgrade price waived.
  • Designed and assembled in-house.
  • T304L 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.
  • 300 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.

  • Limited lifetime warranty.

Fitment Guide

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Fitment Guide

Fitment Guide

Start Year End Year Make Model Submodel Cyl Lit Fuel FuelDel ASP EngDesg Notes

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