Exhaust› Exhaust Pipes, Systems and Components

Alpha Competition

Decat Downpipes

$609.99

SKU: AC-B9RS-DP

In Stock
In Stock
Ships by Sep 12
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Alpha Competition Decat Downpipes are designed for the Audi RS4 B9 and RS5 F5 models without OPF/GPF. Manufactured from 100% T304 stainless steel with handmade TIG welds, these downpipes offer a direct fit between the turbos and front pipes.

They are engineered to remove the catalytic converters, providing an aggressive sound and a measured gain of 34hp on a stage 1 engine. An assembly kit is included for installation.
Show original supplier description
The Alpha Competition Decat Downpipes are a high-performance exhaust component specifically designed for the Audi RS4 B9 and RS5 F5 models that are not equipped with OPF/GPF (Otto Particulate Filter/Gasoline Particulate Filter). Constructed from premium 100% T304 stainless steel, these downpipes feature handmade TIG welds for superior durability and a clean finish. The pipe diameter transitions from 4.5" (114.3mm) down to 3" (76mm), allowing for optimized exhaust flow. These downpipes are intended to remove the factory catalytic converters, which contributes to an aggressive exhaust note and improved performance. A gain of approximately 34hp is noted on stage 1 tuned engines. It is mandatory to perform an ECU calibration after installing these downpipes. These downpipes are explicitly not compatible with versions of the Audi RS4 B9 or RS5 F5 that are equipped with OPF/GPF.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandAlpha Competition
Part NumberAC-B9RS-DP
CategoryExhaust

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

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