Carbon Fiber Rear Bumper Diffuser For Audi A5 / S5 B9 2017–2019 | KB Style Dual Side Exit

Transform the rear end of your Audi A5 or S5 with this KB Style carbon fiber rear bumper diffuser, featuring an aggressive dual-side double-exit design built specifically for the B9 generation (2017–2019). One of the most impactful visual upgrades you can make to the rear of your car — no body shop, no full bumper replacement.

Compatible vehicles

✅ Audi A5 B9 (F5) S-Line — Coupe & Sportback — 2017, 2018, 2019 ✅ Audi S5 B9 (F5) — Coupe & Sportback — 2017, 2018, 2019 ⚠️ Audi A5 B9 (non S-Line base trim) — fitment not guaranteed; the base bumper uses different mounting points and exhaust outlet positions ❌ Audi A5 / S5 B9.5 (2020–2024) — does NOT fit; the facelift bumper has a revised lower section ❌ Audi RS5 B9 — does NOT fit; the RS5 uses a completely different rear bumper with wider exhaust cutouts

Important: S-Line / S5 bumper required

S-Line, non-S-Line, and S5 bumpers differ in shape and mounting points — never assume universal fitment. This diffuser is designed around the S-Line and S5 sport bumper profile. If your A5 is a base model without the S-Line package, the exhaust outlet positions and lower bumper shape will not align correctly. 

About the dual-side double-exit design

This diffuser features two exit openings — one on each side — giving the rear end an RS5-inspired, wide-body look. If your car does not already have dual-side exhaust exits, modifications to the exhaust will be required to make use of both openings. If you are running a single-exit or centre-exit OEM exhaust, the diffuser can still be fitted aesthetically, but only one exit will be functional unless you have your exhaust modified by a specialist. 

Features

• Real carbon fiber construction — not ABS, not hydrodipped carbon-look plastic
• Natural gloss black 2×2 twill weave finish
• Dual-side double-exit design — RS5-inspired aggressive rear profile
• Lightweight — far lighter than factory plastic valance
• Scratch-resistant and UV-protected clear coat finish to prevent fading or discolouration
• Designed to replace the factory rear valance/diffuser at OEM mounting locations
• No bumper cutting required for standard S-Line / S5 fitment

Installation notes

Professional installation is strongly recommended. The rear bumper must be removed to install this diffuser properly. If your exhaust exits are not already dual-side, an exhaust specialist will need to modify or reposition your tips to align with the openings. Hardware is not included — use quality self-tapping screws or bolts at the mounting tabs for a secure fit. 

Specifications

Material: Real Carbon Fiber Finish: Gloss Black (natural carbon weave) Style: KB Style Design: Dual Side Double Exit Colour: Carbon Black Fitment: 2017–2019 Audi A5 S-Line / S5 B9 (F5) — Coupe & Sportback Installation: Replaces factory rear valance at OEM mounting points (bumper removal required) Condition: Brand new

Care tip

Apply UV protectant to the gloss black carbon surface every 3–6 months to reduce fading, and inspect mounting hardware annually for loosening due to thermal expansion.