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Rework the Entire Rear Lower Profile in Real Carbon Fiber
Give your 2020–2024 Audi A4 or S4 B9.5 Sedan a deeper, more defined rear stance with a one-piece carbon fiber diffuser shaped around the compatible factory bumper and exhaust area.
One Full-Width Rear Diffuser Assembly
This is the complete carbon fiber diffuser component shown off the vehicle—not a pair of small side deflectors or a universal decorative strip.
Exhaust Tips and Vehicle Accessories
Exhaust tips and other accessories visible in installed photos are shown for styling reference and are sold separately.
A Complete Rear-End Transformation
Designed for owners who want more visual impact than small corner add-ons while retaining a model-specific, integrated appearance.
Full-Width Design
Reshapes the complete lower rear profile with a deeper center section and defined outer exhaust surrounds.
Real 3K Dry Carbon
Visible woven carbon fiber provides natural depth and a premium finish rather than a printed carbon pattern.
Model-Specific Contours
Developed around compatible B9.5 A4/S4 Sedan rear-bumper proportions and mounting areas.
Reinforced Mounting
Uses compatible factory screw locations with automotive adhesive support; no new holes are listed as required.
Confirm Your Rear Bumper Before Ordering
| Compatible Models | 2020–2024 Audi A4 / S4 B9.5 Sedan |
|---|---|
| Body Style | Sedan only |
| Required Configuration | Compatible, unmodified rear bumper and exhaust layout matching the product photos |
| Not Compatible / Not Listed | A4 Allroad, Avant/wagon, B9 pre-facelift (2016–2019), RS4, or vehicles with incompatible aftermarket rear-bumper or exhaust modifications |
Photo confirmation is required for this large model-specific component. Email your model year and clear rear-view photos to service@asigncar.com so the bumper and exhaust layout can be checked before shipment.
Check the Exhaust Layout Too
The diffuser includes shaped exhaust openings, so outlet position and tip dimensions affect the final appearance and clearance.
Compare Before Ordering
Use the installed photos to compare your current exhaust outlets with the diffuser openings. Modified exhaust systems require an additional fitment check.
Aftermarket Tips Are Sold Separately
Compatible exhaust tips may create a more complete visual match, but they are not included with this diffuser.
Choose Your Finish
Glossy Carbon
A reflective clear-coated finish that highlights the 3K weave and pairs naturally with other gloss carbon exterior parts.
Matte Carbon
A lower-reflection surface with a more understated, technical appearance.
Installation Overview
Because this is a large full-width exterior component, professional installation is recommended for accurate alignment and exhaust clearance.
Verify and Test Fit
Confirm bumper contours, mounting points, symmetry and exhaust clearance before exposing any adhesive.
Prepare the Area
Access the relevant original screws and lower trim as required, retaining reusable factory hardware.
Align and Secure
Position the diffuser, reinstall the compatible original screws and press all adhesive areas evenly.
Inspect and Cure
Recheck fasteners and exhaust clearance, then avoid washing or heavy water exposure for 72 hours.
Complete Diffuser Component
- 1 × full-width carbon fiber rear diffuser
- Pre-applied automotive adhesive tape
- Exhaust tips are not included
At a Glance
- Material: real 3K dry carbon fiber
- Finish options: glossy or matte
- Mounting: compatible factory screw points with adhesive support
- Approximate weight: 3 kg
Frequently Asked Questions
Is this the complete rear diffuser or only the side pieces?
It is one full-width rear diffuser component. It is not the separate two-piece rear diffuser side-deflector set.
Is this a simple adhesive overlay?
No. This is a large full-width component secured through compatible factory screw locations with adhesive support. Access to the original lower trim is required during installation.
Does it fit every 2020–2024 Audi A4 or S4?
Compatibility is limited to listed B9.5 Sedan configurations with a matching rear bumper and exhaust layout. It is not listed for the A4 Allroad, Avant/wagon or RS4.
Does installation require drilling?
No new drilling is listed for a compatible vehicle. The diffuser uses relevant original screw locations together with automotive adhesive support.
Are exhaust tips included?
No. Exhaust tips are sold separately. Confirm the position and size of your exhaust outlets before ordering.
Can it be used with an aftermarket exhaust?
Possibly, but compatibility is not assumed. Send rear and close-up exhaust photos for a clearance check before ordering.
Can I install it myself?
Basic tools are required, but professional installation is recommended because full-width alignment, secure mounting and exhaust clearance must all be checked.
How should I care for the carbon finish?
Use a soft microfiber cloth and pH-neutral automotive cleaner. Avoid abrasive compounds, harsh brushes and aggressive polishing, especially on the matte finish.
Complete the Rear Setup
Compatible real carbon fiber exhaust tips are available separately. Confirm your exhaust configuration before ordering either component.
View Compatible Exhaust Tips
