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The CMST widebody kit for the Audi S3 saloon (8V) is a multi-piece conversion that combines an FRP front bumper and flared fenders with carbon-fibre aero — a front lip, vented bonnet, side-skirt extensions, a light-integrated rear lip and a boot spoiler. Unlike a bolt-on lip kit, this package widens the car: six-piece front fenders and six-piece rear arches push the bodywork out over wider wheels and tyres, turning the discreet S3 into a properly aggressive widebody. It is built for the 8V-generation S3 saloon and mixes materials by function — FRP where panels are large and impact-prone, carbon where weight and finish matter most.

• Vehicle: Audi S3 saloon (8V) — also suits A3 saloon with S3 conversion
• Fitment years: 8V generation (2013-2020), pre- and facelift bumper variants differ
• Material: FRP front bumper, fenders and arches; carbon fibre lip, bonnet, skirts, rear lip and wing
• Key pieces: Front bumper (with plate mount), front lip, vented bonnet, front fenders (6-pc), rear arches (6-pc), side-skirt under-lips, rear lip with lights, rear wing
• Finish: FRP supplied in primer for paint; carbon in gloss-lacquered twill weave
• Stance: Widebody — requires wider wheel/tyre and aligned arch clearance

The S3 has always been a fast car wearing a sensible suit: a four-ring badge, quattro all-wheel drive and a sub-five-second 0–100 km/h time hidden inside the same shell as a base A3. This kit is the antidote to that anonymity. Here is what it adds, why CMST mixes FRP and carbon, and what a widebody conversion actually involves.

The front: bumper, lip and vented bonnet

The front is where the kit makes its first statement. CMST replaces the factory front bumper with an FRP unit that opens up a far larger lower intake — the source describes it as a "big mouth," and that is exactly the effect: a wide, hungry-looking aperture that changes the car's whole expression. A number-plate mount is moulded in, so Australian plate fitment is straightforward.

Beneath the new bumper sits a carbon-fibre front lip with large folded corners. The lip defines the leading edge and adds the kind of splitter-style geometry the standard S3 lacks. Above it, a carbon bonnet with functional vent openings replaces the steel original — the vents help extract heat from the turbocharged 2.0 TFSI engine bay, and the carbon construction trims weight from the very front of the car, which is exactly where reducing mass helps handling balance most.

The sides: widebody fenders, arches and skirts

This is what separates a widebody from a lip kit. The front fenders are supplied as a six-piece set and the rear arches as another six-piece set, all in FRP. Flaring the arches lets the S3 run a wider, more aggressive wheel-and-tyre package without the rubber fouling the bodywork — the visual width and the mechanical grip arrive together. Carbon side-skirt under-lips bridge the gap between the front and rear arches, following the factory side crease so the widened body still reads as one continuous line rather than a set of bolt-ons.

Because the arches are FRP and supplied in primer, they are painted to match the car — which is what lets a widebody S3 look factory-finished rather than patched together. Getting the arch-to-door and arch-to-sill gaps even is the most skill-intensive part of the whole conversion, and the part most worth handing to an experienced installer.

The rear: lip with lights, diffuser geometry and wing

At the back, the carbon rear lip integrates a reverse/fog light — a genuinely practical touch on a widebody, since the wider rear bumper can otherwise obscure rear visibility in fog or heavy rain. The lip's lower section carries diffuser-style strakes that tidy the airflow leaving the underbody. Topping the boot is a carbon rear wing that gives the rear deck a motorsport profile to match the widened arches. The result is a rear that finally looks as fast as the S3 drives.

Why CMST mixes FRP and carbon fibre

The material split is deliberate, not a cost compromise. FRP (fibreglass-reinforced plastic) is used for the front bumper, fenders and arches because those panels are large, take the most stone and kerb abuse, and need to be painted body-colour anyway — FRP holds a paint finish well and is easier to repair if it meets a kerb. Carbon fibre is reserved for the lip, bonnet, skirts, rear lip and wing, where its low weight and exposed twill finish add the most value: a carbon bonnet saves meaningful mass over steel, and an exposed-weave lip and wing read as a genuine material against the paint.

If you want to understand the trade-offs in more depth, our overview of the CMST carbon fibre body kit range walks through where carbon earns its premium and where FRP is the smarter choice. For S3-specific pieces, the CMST body kit collection for Audi lists the components individually so you can build the conversion in stages.

What a widebody conversion involves

A widebody is a bigger job than a lip kit, and it is worth being clear-eyed about it. The FRP panels arrive in primer and must be painted to match — budget for paint and colour-matching as part of the project. Fitting the fenders and arches involves working with the existing mounting points and, on some setups, the arch liners; the skirts and lips mount with a mix of fixings and automotive adhesive. Once the body is wider, the wheel and tyre package and the alignment need to suit the new arch clearance, so a corner-weight and alignment check after fitting is sensible.

Two ongoing notes. The carbon pieces should be sealed and treated like paint to keep the lacquer from yellowing under Australian sun. And because the front bumper and lip sit lower and further forward, driveway approach angles need more care than on a standard S3.

The CMST Audi S3 widebody kit is a mixed-material conversion for the 8V S3 saloon: an FRP front bumper, six-piece fenders and six-piece arches widen the body, while carbon fibre supplies the front lip, vented bonnet, side skirts, light-integrated rear lip and boot wing.

Frequently asked questions

Which Audi S3 does this widebody kit fit?

It is designed for the 8V-generation Audi S3 saloon (2013-2020). The front bumper differs between the pre-facelift and facelift S3, so confirm your build year. The kit also suits an A3 saloon owner doing an S3-style conversion, provided the matching bumper variant is specified.

Is the kit carbon fibre or fibreglass?

Both, by design. The front bumper, front fenders and rear arches are FRP (fibreglass-reinforced plastic) because they are large, paint-matched panels that take the most abuse. The front lip, bonnet, side skirts, rear lip and wing are carbon fibre, where low weight and an exposed twill finish matter most.

Do I need wider wheels and tyres?

Yes. The whole point of a widebody is the extra arch clearance, so a wider wheel-and-tyre package is what fills the flared fenders correctly. After fitting, an alignment and clearance check ensures the tyres clear the arches through full suspension travel and steering lock.

Will the FRP panels come painted?

No — FRP pieces are supplied in primer, ready for paint. They are sprayed to match your car's colour during fitment, which is what makes a finished widebody S3 look factory rather than patched. The carbon pieces arrive in a gloss-lacquered weave and are not painted over.

Does the rear lip really have a built-in light?

Yes. The carbon rear lip integrates a reverse/fog light, which restores the rear visibility a wider bumper can otherwise reduce — a practical detail for wet-weather and night driving in Australia.

Can I fit the kit in stages?

Yes. Many owners start with the carbon front lip and bonnet for an immediate change, then add the widebody fenders, arches and skirts later. Building in stages spreads the cost and the paint work, though planning the wheel package early avoids buying twice.

Want to spec an S3 widebody for your build? Browse the CMST body kit collection for Audi at AME Motorsport, add the carbon vented bonnet from the CMST hood range for Audi, or talk to us about professional widebody fitment in Australia for your exact S3.