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The CMST widebody kit transforms the Honda Fit GK5 (Jazz GK5) from a practical hatchback into a visually aggressive wide-track build, adding flared wheel arches, extended side skirts, and reshaped front and rear bumpers that accommodate wider tyre and wheel combinations. This build — completed on a Beijing-market GK5 — demonstrates the full CMST widebody package fitted to the third-generation Fit platform, which shares its chassis with the Jazz GK5 sold in Australia from 2014 to 2020.

• Vehicle: Honda Fit / Jazz GK5 (third generation, 2013–2020)
• Kit type: CMST widebody (full body kit)
• Material options: FRP (fibreglass-reinforced plastic) or carbon fibre
• Key pieces: Front bumper, front canards, wide front fenders, side skirts, wide rear fenders/wheel arches, rear bumper, rear diffuser
• Wheel clearance: Widens each side by approximately 40–60 mm per axle (varies by spec)
• Finish: Supplied raw for customer paint or carbon weave exposed

Why Widen a GK5?

The GK5 platform is a popular canvas for Japanese-style compact car builds. Its 1,525 mm factory width is relatively narrow by modern standards, which constrains how wide a wheel-and-tyre combination can be run before excessive wheel offset becomes necessary. A widebody kit resolves this by extending the bodywork outward over a wider track width, allowing fitment of wheels in the 9–10" wide range with aggressive offsets (ET15–25 range) while keeping the tyre within the body line.

Beyond aesthetics, a wider track in combination with a lower ride height and appropriate suspension tuning genuinely improves lateral stability through corners — wider track means a larger moment arm against lateral force, reducing the tendency for a lightweight hatchback to feel skittish under hard cornering. This build pairs the CMST widebody with the Honda Fit's inherently stiff GK5 body shell, which benefited from Honda's Advanced Compatibility Engineering (ACE) body structure that stiffens the B-pillar and rocker areas — the same areas now being covered by the widebody skirts.

Front Bumper and Canards

The CMST front bumper for the GK5 widebody replaces the factory unit entirely rather than adding to it. It carries a lower splitter section and integrated canard positions at each outer corner. The canards on this kit angle outward and rearward, serving two purposes: they visually signal the increased width of the front axle, and at speed they generate a small amount of downforce at the front axle by managing the pressure differential between the upper and lower surfaces of the extended bumper.

Fitment of the front bumper requires removal of the factory front bumper assembly, which on the GK5 is retained by:

• Two 10 mm bolts behind each front headlamp unit
• A series of push-pin clips along the top edge of the bumper cover
• Two 10 mm bolts at the underside of the bumper to the front sub-frame undertray

The CMST replacement bolts to the same locations. Headlamps, grille, and fog lamp units transfer across to the new bumper. On FRP units, minor trimming with a rotary tool may be required to clear fog lamp housings precisely.

Wide Front Fenders

The widened front fenders are the defining visual element of any widebody kit. The CMST GK5 fenders replace the factory stamped-steel front guards entirely. They extend the outer body line by approximately 40–50 mm per side at the widest point of the wheel arch, accommodating wheels up to approximately 10" wide with an aggressive low-offset fitment.

Fender replacement on the GK5 requires:

• Removal of the front door (or at minimum the front door weatherstrip) to access the rear fender mounting flange
• Disconnection of any front turn signal repeaters in the fender if fitted
• Removal of eight to ten bolts around the fender perimeter

FRP widebody fenders benefit from being bolted and bonded — adhesive seam sealer applied to the inner lip prevents water ingress into the A-pillar joint. Carbon fibre fenders on this kit come with pre-drilled mounting holes and a finished inner surface.

Side Skirts and Rocker Extensions

The CMST widebody side skirts for the GK5 run the full length of the rocker panel and extend further downward than the factory sill trim, lowering the visual centre of gravity of the car. They attach via a combination of VHB tape and OEM-style clips to the factory sill panel. The side skirt on this kit also incorporates a visual bridge between the flare profiles of the front and rear fenders, maintaining a coherent arc from wheel arch to wheel arch along the car's flank.

Wide Rear Fenders and Wheel Arches

The rear fenders present the most labour-intensive part of a widebody fitment on any car. Unlike the bolt-on front fenders, widening the rear of most hatchbacks requires either overfender-style bolt-on arches or full replacement of the quarter panel. The CMST GK5 kit uses bolt-on rear overfenders that sit over and extend the factory rear quarter panel edge. This approach preserves the factory rear quarter (no cutting required in this configuration), but does require the factory wheel arch lip to be rolled or pulled flat before the overfender is seated — a process done with a dedicated fender rolling tool to avoid cracking the factory paint behind the arch lip.

Rear Bumper and Diffuser

The rear bumper section completes the widebody appearance by matching the visual width of the rear fenders with an extended rear fascia. The lower diffuser section features a series of vertical fins that improve the visual cohesion of the wide rear stance and direct exhaust flow downward and rearward. On builds using a performance aftermarket exhaust, the diffuser exit geometry should be checked against exhaust tip diameter and position before fitting.

Wheels and Tyre Fitment

The widebody kit's purpose is to enable a wider wheel and tyre combination. This build runs wheels substantially wider than the GK5's factory 185/55R15 fitment. When specifying wheels for a widebody GK5, check:

• PCD: Honda GK5 uses 4×100 PCD
• Centre bore: 56.1 mm (hub-centric rings required for most aftermarket wheels)
• Offset: Factory is ET45; widebody builds typically run ET15–ET25 on the rear to fill the extended arch
• Tyre clearance: Confirm tyre sidewall clears the inner guard at full suspension travel — a clay or zip-tie test is the minimum check before daily driving

For the full range of widebody and carbon fibre body kit options at AME Motorsport, browse the CMST body kit collection. The carbon fibre body kit range covers front lips, diffusers, fenders, and full kits for a wide selection of platforms. To explore CMST's complete product range, visit the CMST collection page.

Frequently Asked Questions

Does the CMST GK5 widebody kit require cutting the factory body panels?

The front fenders are fully replaced — removed and swapped, no cutting. The rear uses bolt-on overfenders over the factory quarter panel, which requires the factory arch lip to be rolled flat but does not require cutting the steel body. Minor trimming of bumper covers may be needed for precise fitment of fog lamps or sensors.

Is the CMST Honda Fit GK5 widebody available in Australia?

The Honda Fit GK5 is sold in Australia as the Jazz GK5 (2014–2020). The CMST widebody kit fits the same shared platform. AME Motorsport sources CMST products for the Australian market — enquire through the CMST collection page for current stock and lead times.

What wheel size suits the CMST GK5 widebody?

The widebody accommodates wheels in the 16–17" diameter range at 8.5–10" width with offsets in the ET15–ET25 range on the rear axle. Exact fitment depends on tyre profile and suspension setup. A 205/45R16 or 215/40R17 tyre is a common starting point for widebody GK5 builds.

Can I daily drive a widebody GK5?

Yes, with appropriate tyre and wheel fitment. The CMST kit adds no weight that meaningfully affects driveability, and the ABS or FRP construction is durable in daily use. Ground clearance is reduced slightly at the front splitter, so steep driveway entries should be approached at an angle.

Is professional fitting recommended?

Front fender and rear overfender work, combined with fender rolling, is best handled by a shop experienced in body kit fitting and panel alignment. DIY is possible for experienced enthusiasts, but fender rolling in particular can crack factory paint if not done correctly.

What is the difference between FRP and carbon fibre for this kit?

FRP is heavier and requires primer and paint to finish. Carbon fibre (dry carbon) is lighter and carries an exposed weave finish under UV-stable clear coat. For a widebody kit on a daily driven car, FRP painted to body colour gives a factory-style integration; carbon fibre is the choice when the weave texture is part of the visual statement.