2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber
2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber
2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber
2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber
2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber
2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber
2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber
2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber

Vendor:K2 Industries

2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber

Sale price$969.99 USDRegular price $1,065.00 USD
Shipping Option
Shipping Option: Air Freight (1-2 Weeks)
In stock, ready to ship

2020–2022 Audi A4 S-Line / S4 B9 Sedan Rear Diffuser – Pre-Preg Dry Carbon Fiber

Give the rear end of your Audi A4 S-Line or S4 B9 the same attention as the front with this pre-preg dry carbon fiber rear diffuser. Molded to the factory rear bumper lines, it adds depth and sharp edges for a refined, motorsport-inspired presence without going over the top.

Build

  • Material: Pre-preg dry carbon fiber in a 3K twill weave — the resin is pre-impregnated into the weave under controlled conditions before autoclave curing, giving superior strength while keeping weight to a minimum, a consistent weave, and a lighter finished component than standard wet carbon
  • Manufacturing: Autoclave cured, precision 3D-moulded for accurate fitment
  • Surface finish: Deep high-gloss black clear coat that highlights the 3K twill weave and provides long-lasting surface protection
  • Configuration: Single-piece diffuser for the lower rear bumper

Design & Aerodynamics

  • Aggressive stance: Diffuser profile adds depth and sharp lower-rear edges for a more planted, motorsport-inspired rear end
  • Carbon aesthetic: Refined 3K twill dry carbon weave and high-gloss clear coat deliver premium contrast against the factory paint
  • Factory-style integration: Precision-molded to the contours of the factory rear bumper for a clean, seamless fit

Fitment

  • 2020–2022 Audi A4 S-Line B9 Sedan
  • 2020–2022 Audi S4 B9 Sedan
  • Fits the A4 S-Line and S4 factory rear bumper only — not compatible with the standard non-S-Line A4 or aftermarket bumpers

Package Contents

  • 1 × pre-preg dry carbon fiber rear diffuser
  • Mounting screws for installation

Installation

  • Screw-mounted: Secures with the included mounting screws for a secure, rattle-free fit
  • Drilling required: Screw fixing pierces the bumper, so this is a permanent modification rather than a reversible fit
  • Surface prep: Clean and degrease the rear bumper at the fixing locations before installation
  • Alignment: Dry-fit and check the diffuser sits centred and even across the bumper before driving any screws
  • Professional installation recommended for correct positioning, panel alignment, and a clean finish

Before You Install

  • Confirm your car is an A4 S-Line or S4 B9 Sedan (2020–2022) before ordering — this will not fit the standard non-S-Line A4
  • This is a permanent, screw-mounted fitment — dry-fit and confirm placement carefully before driving any screws, as holes cannot be undone
  • Take care when parking rear-in — lower rear panels sit close to kerbs and parking blocks

Ships within 1-2 business days.

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FAQs

Please read our FAQs page to find out more.

Are OEM products more expensive than aftermarket alternatives?

OEM products might have a higher upfront cost compared to aftermarket parts, but their superior quality and durability often make them a more cost-effective choice over time. Investing in OEM ensures you’re getting parts specifically designed for your vehicle, which can lead to better performance and longevity.

Can I purchase OEM parts online or do I need to visit a dealership?

You don’t need to visit a dealership to get OEM parts. You can conveniently purchase genuine OEM components from authorized distributors and reputable online retailers like Turbo Tech Performance. Our online store provides a wide selection of high-quality parts delivered straight to your door.

Are parts from brands like Mopar, ACDelco, and Motorcraft interchangeable between different vehicle brands?

No, parts from Mopar, ACDelco, and Motorcraft are typically designed for specific vehicle brands. It’s crucial to ensure compatibility with your vehicle’s make and model by checking part numbers and consulting with a knowledgeable expert.

Can I install OEM parts myself, or is it better to have a professional handle it?

While some OEM parts can be installed by DIY enthusiasts, the complexity of installation can vary. For the best results and to ensure proper fitment and performance, we recommend having a trained mechanic install the parts, especially if you’re unfamiliar with automotive repairs.

Do OEM parts come with a warranty?

Yes, many OEM auto parts come with a manufacturer’s warranty that covers defects or issues. Be sure to check the warranty details for each part at the time of purchase, and keep your receipt for any potential warranty claims.

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