The Audi A4 lineup, including the high-performance S4 and RS4 models, has long been known for its blend of luxury, precision, and dynamic road presence.
Different generations such as B8, B8.5, B9, and B9.5, all feature new designs and an unsurpassed blend of elegance and sporty aggression.
But the potential that customization brings with the Audi A4 platform is huge.
No matter the model you’re driving, there are several mods that can completely change the appearance and performance of your Audi on the road.
From upgraded engine parts to a sportier look & dynamic lines, small incremental upgrades are what make your A4, S4, or RS4 stand out from the crowd and give it a new feel like no other.
Exterior mods for the Audi A4 / S4 / RS4
With Audi’s grille-forward design, there is still plenty of room for improvement, which you can take even further depending on your taste.
A handful of targeted upgrades will help sharpen up its aggression and make it look more modern and performance-inspired.
Honeycomb Grilles
The front of an Audi makes a bold statement, and upgrading it instantly transforms the car’s character. A honeycomb grille is perhaps the single most important addition to any exterior Audi transformation. These grilles will not only replace your factory horizontal bars with a sporty, deep mesh pattern, but also highlight your vehicle’s presence on the road.
They're really good on the B8 / B8.5, A4, and S4, with the front end already quite small but in need of a little extra visual depth. The same is true for B9 and B9.5 owners looking to give their A4 a touch of class without overdoing it.
A high-quality honeycomb grille provides:
- The RS-look by giving a more dynamic front end
- Improve air flow to the cooling system
- A unique feel compared to factory designs
- Simple plug-and-play installation and perfect fitment with OEM mounting points
Front Lips & Splitters
Another mod that really ups the visuals of the front-end is the front lip splitter, which extends out the lower bumper, allowing a wider, more grounded look. Since the A4 and S4 have clean, subtle body lines, the front lip can give you that sporty look without becoming overbearing.
Depending on your model, there are a few options:
- Gloss black ABS lips
- Carbon-style variants
- Multipurpose design for a more aggressive setup
A front lip also helps the car sit visually lower at the nose, giving it a more cohesive, performance-focused look, and pairs well with honeycomb grilles for a more cohesive look on the front end.
Mirror Caps
Mirror caps are a popular side exterior mod for the immediate styling effect they provide. Available in gloss black or carbon fiber styles, these caps mimic visual cues from RS and black optics packages.
Mirror cap upgrades provide:
- Sportier, more premium appearance
- More contrast against lighter body colours
- OEM+ look, which will perfectly suit the A4’s design
This is one of the easiest and more affordable mods you can have installed on your car.
Side Skirts & Extensions
Side skirts give the car a lower, cohesive look, bridging front and rear styling improvements together. They give it an elongated, more dynamic silhouette and help the A4 look a little more planted on the road.
They are especially effective when combined with:
- A front lip splitter
- A rear diffuser
- A trunk lip spoiler
A cohesive profile from the side gives the car a sportier stance while keeping with the A4’s classier look.
Rear Diffusers
Of all the modifications for modern Audis, few grab attention like a good rear diffuser. These new-look panels feature sculpted fins, deeper contours, and a look inspired by the RS that enhances its lightness and performance.
Diffusers available for A4/S4/RS4 models:
- Accentuate the rear bumper
- Combines with factory or aftermarket exhaust tips
- Give it a cool racecar look
- Improve airflow dynamics
- Make your sedan look more upscale
From B8 to B9.5, diffusers still are the most visually impactful rear-end upgrade you can choose.
OEM+ Rear Spoilers
A rear lip spoiler is a subtle choice, as it complements the car's lines and gives the rear end of your vehicle more depth instead of looking flashy. It’s arguably the most popular addition to any car, including the Audi A4 range because of its cost, looks, and ease of application.
GCA stock a range of spoilers for the Audi A4/S4/RS4 range including:
- Gloss black lip spoilers
- Carbon-style options
- Renntech spoilers
- Ducktail spoilers
- PSM style spoilers
It is a perfect mod whether you’re chasing the OEM+ look or want to get something a bit sportier, and with plenty of options available, you can really make your car truly unique.
Fog Light Covers and Lower Grille Inserts
Sometimes the small additions make the biggest impact. Modernize the bumper with a new sporty look by changing out the factory plastic inserts for new mesh or gloss black fog light grilles. They match with honeycomb grills and front lips to give the car a nice, aggressive look.
These pieces offer:
- Consistent, professional front-end appearance
- A darker and a little more aggressive theme
- Enhanced air flow in certain models
Performance Mods for the Audi A4/S4/RS4
The Audi A4/S4/RS4 already has great performance with their stock models, but we know there’s always room for improvement.
The following are some of our favourite performance upgrades that will deliver results you will actually feel behind the wheel of your A4.
Valved Sport Exhaust Systems
A valved exhaust system completely transforms the driving experience. With the flick of a button, the valve can open and close, making it easy to switch between quiet and aggressive modes.
They’re perfect for those who want comfort during your daily drives, but full sound of the engine when it’s time to unleash.
It’s the pinnacle of performance and a worthy upgrade for your A4, S4, or RS4 if that’s what you’re chasing.
Downpipes
If you’re upgrading your exhaust, it’s only practical to also upgrade your downpipes.
Upgraded downpipes in your Audi A4 helps replace restrictive factory pipes, by improving your exhaust flow and turbo spool for better throttle response and a more aggressive sound.
They’re a popular choice when trying to improve both sound and performance and paired with a valved exhaust, you’ll get a deeper tone, faster response, and a noticeable increase in power.
Make sure you always check your local regulations before installing downpipes, as some aftermarket pipes may affect emissions compliance.
High-flow Intakes
A high-flow intake helps your Audi A4, S4, or RS4 breathe more freely by increasing airflow to the engine while reducing restriction from the factory setup.
The result is sharper throttle response, smoother power delivery, and a more pronounced induction sound that adds character without being over the top.
It’s one of those upgrades you feel every time you accelerate, making the car feel more responsive and connected.
Intercoolers
If you’re repping any of the above performance upgrades, or just pushing your Audi that little bit harder, then an intercooler is a must have.
Intercoolers help reduce intake temps, helping your engine maintain power under heavier load or hotter conditions.
Factory intercoolers can suffer from heat soaking, leading to reduced performance. A larger, more efficient intercooler fixes the issue by keeping intake air cool and dense for consistent power output.
What Mod Should You Start With?
No matter your budget or vision, there’s a modification for your Audi A4, S4 or RS4. If you’re unsure where to start, consider the following:
- For better visual appeal - start with a front splitter or rear spoiler. Both are easy to install and have a bit of visual impact.
- For better performance - It’s hard to go past an upgraded valved exhaust system.
- For the complete package - Exhaust, downpipes, spoilers, splitters, intercooler - your budget is the only thing stopping where you can take your car here.
The Top Mods for Your Audi A4 / S4 / RS4
Whether you drive a B, B8.5, B9, or B9.5, the Audi A4 family continues to be one of the best models for visual and performance customizations.
You can easily enhance them with handsome upgrades like honeycomb grille, rear diffuser, side skirts, or mirror caps, or go under the hood with a new exhaust or downpipes, all which dramatically change the look and feel of your A4/S4/RS4 for the better without losing that sophisticated Audi-style.
