Theon Design has revealed its latest bespoke Porsche 911 (964) commission, codenamed GBR003 – the company’s debut open-top Targa model.

As with every Theon Design commission, the all-carbon bodied, six-speed manual, 4.0-litre naturally aspirated GBR003 is an entirely bespoke creation, enhanced from the ground up at Theon’s production facility, nestled in the heart of Oxfordshire’s ‘motorsport valley’.

Finished in a one-off, paint-to-sample Pastel blue, over liquorice leather, the Targa is the ultimate realisation of a client’s Porsche 911 fantasy, combining OEM+ design and engineering capabilities, hand-crafted luxury touches, with cutting-edge technology and manufacturing processes.

GBR003 is executed with Theon’s customary obsessive attention to detail and laser-focused engineering rigour, resulting in a car that delivers the sensory thrills of open-top motoring without any dynamic compromises.

To ensure the Targa drives with signature Theon fluidity and control, the team has developed a system of bespoke carbon fibre strengthening ‘tubs’, which are bonded to the floor of the chassis, significantly improving torsional rigidity while keeping additional weight to the absolute minimum.

Theon co-Founder Adam Hawley explains: “With our first Targa commission, the whole Theon team has been determined to set new standards for an air-cooled open-top Porsche 911 driving experience. We’ve been totally focused on honouring and distilling the air-cooled recipe, forensically honing every element to create a rewarding, analogue classic 911 that combines the sensory richness of Targa motoring with razor-sharp handling and visceral modern performance.”

The Theon Process

GBR003 takes a Porsche 911 (964) Carrera 2 Targa as its base. The donor car has been stripped back to bare metal before being meticulously restored over thousands of hours by Theon’s passionate technicians.

The body for GBR003 is all-carbon, aside from doors which remain steel for side impact protection. As with all Theon builds, each panel has been digitised and modelled in 3D design software to ensure a perfect fit. Thanks to the carbon panels, and the use of carbon for the underfloor strengthening, GBR003 weighs in at just 1228kg with all fluids on board, a mere 60kg more than the equivalent Theon coupe.

Innovative chassis strengthening

A bespoke carbon fibre bracing system ensures exemplary underfloor strengthening. The innovative, lightweight solution transforms structural rigidity without adding any undue additional weight – using the same carbon construction technology deployed in Formula One and other forms of elite-level motorsport.

The strengthening system takes the form of two ‘tubs’, created using a laminate ‘sandwich’ of toughened epoxy prepreg carbon fibre and aerospace-grade Nomex honeycomb—conceived to be as strong and light as possible. The tubs are first designed in CAD to perfectly fit the floor of the Targa chassis before being formed to the tightest tolerances using a 5-axis CNC machine.

No stone was left unturned in the pursuit of total rigidity, with the carbon laminate orientation and thickness optimised through CAD structural simulation software to ensure the stiffest possible construction. Once fabricated, the tubs were permanently bonded to the existing chassis and bulkheads to deliver maximum driving stability, even in the most demanding conditions.

Open top thrills without compromise

The carbon strengthening results in transformed levels of structural rigidity, delivering a stable, exceptionally rigid platform. Thanks to this exceptionally torsionally strong base, Theon has been able to replicate the signature handling precision of its celebrated Coupe commissions with an open-top car. The GBR003 drives with sheer modern sophistication and precision and packs a superb range of dynamic capabilities thanks to a switchable, five-stage TracTive Active Controlled Electronics (ACE) damping system.

The switchable damping system has been carefully calibrated for the Targa model over countless test miles, ensuring it delivers across a wide range of environments. The technology elevates the open top air-cooled driving experience to new heights, with exceptional control whatever the scenario, roof on or roof off.  The GBR003 can seamlessly shift from a long-legged and complaint cruiser when sweeping along an A-road, to super tied-down and focused when the time comes to attack a mountain pass.

Defined by attention to detail

Theon’s signature, laser-focused attention to detail is evident in all areas of the build – even those elements housed and hidden deep beneath the car’s carbon fibre skin.

Every element is honed and enhanced to perfection. For instance, an aerospace-grade wiring loom snakes beneath the sculpted body – saving over 20kg, while modern dual air-conditioning compressors, and an all-new electro-hydraulic power steering pump are relocated to the front of the car, tucked low down to aid the 48:52 front to rear weight distribution.

Then there’s the GBR003’s air-cooled beating heart, a 4.0-litre flat six masterpiece. Featuring independent throttle bodies and breathing through dramatic open trumpets, the motor produces 403bhp at 7100 rpm – breaking through the hallowed 100bhp per litre barrier. It remains entirely tractable, with peak torque of 320lb/ft at 5500rpm. Combined with its low kerb weight, the GBR003 always has deep reserves of performance, surging effortlessly towards the horizon whatever the engine speed or gear.

Exploring the upper reaches of the rev band reveals a more savage side to the engine’s character; it pulls with sheer ferocity all the way to the limiter, building power all the way. This unyielding thrust is accompanied by a stunning flat-six howl from the latest iteration of Theon’s custom, switchable and fully ceramic-coated exhaust - rendered all the more life-affirming when the roof is removed.

The updated, bespoke exhaust system gives GBR003 a quieter, more reserved character in normal use, then offering a full motorsport style flat-six cry when the valves open. The valves can be activated manually via a switch in the cabin, and also open automatically when pushing on into the rev range.  

With a lightweight, single-mass flywheel, GBR003 has near-synaptic throttle response, while the slick six-speed manual gearbox – built to 993 RS specification is a sheer joy to row up and down, with carefully repositioned pedals inviting you to heel-and-toe when downshifting – if only to hear the flat-six motor sing.

Thanks to a power-to-weight ratio of 328 bhp per ton – the same as a 991 GT3 – outright performance is modern supercar quick, with a full 993 RS brake setup providing exemplary stopping power.

A thing of beauty inside and out

As with all Theon Design commissions, Hawley – drawing on his background in OEM car design – has obsessed over every aesthetic detail to deliver a cohesive, perfectly formed Porsche 911 shape. This results in a timeless design that is simultaneously purposeful and pretty.

For the GBR003, the carbon body is finished in a bespoke, paint-to-sample pastel blue, with contrasting PORSCHE script – matching the light grey of the Pepita seat centres – along with lighter ‘ghost’ stripes along the sills and bumpers. The colour of the stripes is also matched to the 993 RS brake callipers, which nestle behind 18-inch Fuchs wheels, wrapped in Michelin Pilot 4S rubber – filling the sculpted arches perfectly.

The Targa’s entirely bespoke cabin reflects Theon Design’s commitment to hand-crafted quality, elegantly combining the finest materials for a cossetting yet inherently sporting driving environment. All substrates in the interior are fashioned from carbon to save further weight, then wrapped in sumptuous leather. GBR003 features Theon’s ‘touring’ seat option, optimised for comfortable fast road driving, with sculpted rear buckets that draw inspiration from those in Porsche’s 928. The rear buckets also seamlessly incorporate subwoofers, further enhancing audio quality.

Both front and rear seats are trimmed in the finest liquorice coloured semi-aniline leather, with OEM Porsche Agate grey Pepita centres– as featured in the Porsche 911 (992) Sport Classic interior. The cockpit embodies Theon’s approach, drawing upon and honouring the full sweep of Porsche’s rich heritage, bringing the various elements together into a beautifully resolved, wholly cohesive package, for an elevated but resolutely ‘Porsche’ driving environment.

The interior is replete with modern creature comforts, including a bespoke audio setup featuring Pioneer’s sector-leading P99RS Bluetooth classic stereo unit, paired with Focal amplifiers and six speakers – again by Focal – which are housed in the doors.

Theon’s attention to detail and bespoke approach are further exemplified by the creative installation of Focal subwoofers, which are seamlessly integrated into the cushions of the rear seats. This preserves space within the compact 964 cabin and delivers real depth of audio performance.

Theon has also revised the Targa roof, which has been re-built to the tightest tolerances to ensure a perfect fit with the strengthened 964 shell. Now finished in a modern mohair material, the Targa top folds up neatly and slots into a bespoke carry bag, which fits snugly in the leather lined ‘frunk’.

Hawley concludes: “The prospect of open-top motoring has always been tantalising, but the dynamic reality often underwhelms. With this car, thanks to the innovative carbon-strengthening floor we’ve developed using F1-derived carbon technology, we’ve really taken things to the next level. You get the best of both worlds.

“Everyone who’s driven the Targa during our exhaustive development process has been bowled over by the results; it delivers the rigidity and handling precision of a coupe, but with the added sensory rush of a convertible.

“It’s driving in technicolour: you’re totally engaged by the analogue driving experience and more aware of your surroundings too. Of course, you also get to hear much more of the addictive flat-six howl! As a team, we’re exceptionally proud of the results, and the customer is delighted, too.”

Prices for Theon Design commissions start at £390,000 for Coupes, and £415,000 for Targas. Each car is a totally unique collaboration with the customer and takes 18 months to build. Price excludes donor car, shipping and local taxes.