2017-2020 Audi A4/S4 Carbon Fiber KB Style Diffuser with LED Brake Light | B9 A4/S4

Description

Complete your 2017-2020 Audi A4/S4 B9’s rear end with this carbon fiber KB Style rear diffuser featuring an integrated LED brake light — a dual-function upgrade that adds both aerodynamic presence and active safety. Fits all B9 A4 and S4 variants with quad exhaust cutout, and saves you $500+ compared to dealer-sourced alternatives.

Key Features

• Real 2×2 Carbon Fiber Weave — genuine carbon construction with high-gloss finish
• Integrated LED Brake Light — functional third brake light wired for factory-style operation
• Glossy UV-Protectant Clear Coat — weather and UV resistant for long-term exterior use
• Hardware Included — all mounting bolts and 3M tape in the box
• Quad Exhaust Cutout — designed specifically for quad exhaust tip configurations
• Save $500+ vs. Retail — premium look at a competitive price
• Free USA Shipping via UPS

Vehicle Compatibility

• 2017–2020 Audi A4 Non S Line (B9)
• 2017–2020 Audi A4 S Line (B9)
• 2017–2020 Audi S4 (B9)

Note: All diffusers are made with quad exhaust cutout only.

Installation

Professional installation required. All necessary mounting hardware (bolts and 3M tape) is included. LED brake light wiring connects to existing rear light harness. Estimated installation time: 2-3 hours with basic tools and lift access.

Why Buy From All Audi Spare Parts?

We specialize exclusively in Audi upgrades — every part is verified for B9 A4/S4 fitment before listing. Carbon fiber quality and LED function are both tested by our suppliers. Fast USA shipping and full customer support on every order.