Porsche 911 (992.2) GT3 Manthey Kit review – an even sharper GT3 for an extra £56k

Manthey Racing – the road and race engineering specialists based right next to the Nordschleife – have been winning races with Porsches (including the Nürburgring 24 Hours seven times) and making its road cars quicker since the 1990s. Porsche itself acquired a majority stake in the company in 2013, and in addition to official motorsports programmes and numerous other projects, Manthey creates fully homologated packages of upgrade parts for Cayman and 911 models, made available as ‘kits’. 

This is its new kit for the current 992.2-generation 911 GT3. Although it’s designed to make the GT3 excel on track, it’s fully road homologated. We’ve therefore tested it both on the road and on track, at Thruxton Circuit. 

992.2 GT3 Manthey Kit in detail

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We’ve previously tested the equivalent 992.1 GT3 with Manthey Kit during evo’s 2024 Track Car of the Year test at Cadwell Park. It thoroughly impressed, feeling noticeably different and more incisive than the stock GT3.  Manthey has also released a wild-looking high-downforce kit for the 992 GT3 RS, which became the fastest two-seat road car we've ever timed on evo’s leaderboard at Anglesey circuit.

This new kit for the non-RS, 992.2-gen GT3 has been made available only six months after the car’s launch – a shorter lead time than previously, because Manthey had access to the car’s blueprints and data early in the design process, along with early-bird development time at Porsche’s Weissach wind tunnel and test track. 

From a distance, it looks more like an RS model than a regular GT3, so purposeful are the aero upgrades. There are no changes to the powertrain – the main focus is on aero and suspension. 

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The regular GT3’s adaptive dampers are exchanged for a coilover set-up with passive, hand-adjustable shock absorbers. They adjust four ways, for compression and rebound at high- and low-speed. The front spring rates are 20 per cent stiffer than the standard car’s, partially for stability under braking and also to counter the additional load of downforce.

At the front, the splitter has a slightly upward slant compared with that of the standard car, to catch airflow as early as possible. It’s 12mm longer than the normal GT3 splitter – the maximum possible without infringing pedestrian impact regs. All the kit’s aero surfaces must comply with various legislative demands in multiple markets. That includes the diveplanes bookending the nose at either side, helping to balance the rear wing’s downforce at the front.

> evo Leaderboard lap times – the world's fastest cars tested on track

The rear wing is made from carbonfibre, with a different shape from the regular GT3’s and ‘underwrap’ endplates, designed to work together with the airflow onto the GT3’s ducktail-style lip on its tail beneath the wing. The wing has two manually adjustable angles: a near-flat setting for road use and a steeper angle for the track. Regardless of setting, the kit produces more than double the downforce of the standard GT3. At top speed with the wing in its high-downforce setting (183mph), that translates to 575kg, over 100kg more than the previous 992.1 kit.

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In the lower-downforce setting top speed 194mph, the same as the standard GT3 – because the drag coefficient is the same. Trickily, to retain the GT3’s road-approval homologation, its CO2 and fuel consumption figures must be unchanged. That means, despite the extra downforce, Manthey has had to work to keep the drag coefficient identical. It’s a remarkable trick – a bit like eating more food, yet somehow weighing the same. 

Some of the magic comes from beneath the floor, where aerodynamic surfaces along its entire length help put the air where it’s needed. That includes a variety of turning vanes, made from plastic rather than carbon because they’ll inevitably wear down on track. It’ll no doubt be a point of pride among customers as to how many sets they’ll get through; the more worn down they become, the faster you’re likely to be lapping. Roughly speaking, almost half the downforce comes from the underbody and the rest from airflow above the car.

The rear diffuser is made entirely from carbonfibre, with a two-step design based on Manthey’s 992 RS kit. Adding further visual drama are the aero discs over the rear wheels, for reducing turbulence.

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Not part of the pack but available as an extra option, and fitted here, are ultra-lightweight alloy wheels, made by Manthey in their own factory. They save a total of 6kg compared with the GT3’s regular alloys, and are only 1.4kg heavier than Porsche’s own, very pricey optional magnesium rims. 

The spidery spokes make it easy to spot a further extra option: Manthey’s special, fade-fighting brake pads painted in bright green. They’re available only for the GT3’s PCCB carbon-ceramic disc option at present; Manthey is working on homologating pads for the standard steel brakes too. Braided brake lines are part of the kit.

Topping it all off are Manthey decals and an illuminated logo in the door sill panels. This car also has an optional carbon trim package for the vent shrouds in the nose and engine cover vents at the rear, and tow hooks (optional for the car, mandatory on most trackdays). Even they are a special hybrid blend of alloy and titanium. 

Porsche 911 GT3 with Manthey Racing kit on the road

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Before testing the Kit on track at Thruxton, we have the car to ourselves on the road for a little over 24 hours. Even on the urban and motorway drudgery that makes up the first leg of the journey, the responsive, alert steering makes an impression. Modern GT division Porsches invariably have remarkably responsive front ends but with this car’s touch of extra camber, it’s particularly darty, almost disconcertingly so for the first few corners. 

But you quickly tune in and come to revel in the front tyres’ instant, precise response. In this case, they’re some very fresh-looking Michelin Pilot Sport Cup 2 tyres with N1 labels denoting them as Porsche-specific tyres. It’s a moderately noisy car on the road: expansion joints in the tarmac ricochet rowdily, there’s even more tyre noise than in a standard GT3 and, at low-ish speeds, you can actually hear the rear dampers at work. 

But this is still a very usable car; civilized, even. There’s still Apple CarPlay and a stereo system, even if there’s more background noise for the speakers to compete with than there would be in a more mainstream 911. The bucket seats are even heated. Driving a track-focused car with relatively lightly treaded tyres in relentless rain should be scary but their soft compound is biting into the road surface very well, and the flat-six’s linear, naturally aspirated throttle response makes it easy to put the power down precisely. 

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It helps that there’s not a big wodge of torque at low revs; since there’s no change to the engine’s mechanicals nor its software, the 332lb ft of torque reaches its peak above 6000rpm and peak power is up past eight. The magical 9000rpm redline is still there, and sounds as divine as ever.

A surprising degree of pliancy to the suspension helps, too. While the ride’s certainly firm, it’s not busy or crashy like some track-focused cars. There’s still plenty of composure for road use, and it makes the GT3 really driveable on these rural, soaking roads. Brake pedal feel is fantastic and the pads don’t squeal, unlike many high-performance brakes.

Out here, the pacey steering response comes into its own. The car feels like a normal GT3 only even more precise and even higher-fidelity than before. For every input in a GT3 you get a precise output but in this car, even more satisfyingly so. The body’s movements upon the suspension feel even more measured with speed, too.

The low (albeit adjustable) ground clearance is one of the few weak points from a road usability perspective. This car has a lift function for the nose to get over speed bumps however the low-lying diffuser at the rear is vulnerable, and you do need to take particular care over steep inclines and ramps to avoid grounding it Still, the all-round driveability, in such challenging weather, is thoroughly impressive. 

Porsche 911 GT3 with Manthey Racing kit on track

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By contrast, Thruxton race circuit is sunny and totally dry. For the track element of the test, the rear wing is set to its steepest setting, and the suspension two clicks stiffer. For our opening laps, we’re on the same Michelin Pilot Sport Cup 2 tyres as the road drive. I’ve never been to Thruxton before and it’s a thrilling, eye-openingly quick track, with long corners making vision a challenge, and surface changes and bumps to contend with.

That driveability on the road is here in spades at higher speeds on the track. It gives you confidence from the get go. A standout quality is stability under braking. You really feel the benefit of the stiffer spring rate at the front when braking into the final chicane, sometimes with a little bit of lock on due to the curved approach path. As Manthey intended, it doesn’t ‘fall over’ the outside front wheel as you trail the brakes into a corner, but rather stays stable like a racing car.

You shift into sixth gear at 150mph on the curving back straight on the approach to the chicane; I’m not sure what speed I’m doing when I actually hit the brakes since my widened eyes are busy focused on the jagged-looking apex kerbs – but the Manthey 911 allows extremely late braking. That’s helped by pedal feel as transparent and easy to modulate as on the road. The dampers ride the kerbs well, too.

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Front-end grip feels relentless on the road but the 911’s weight distribution is more evident on track, and there’s more understeer until the front tyres warm up. But they bite well once there’s heat in them and you can feel the additional downforce over a regular GT3 in extra stability in high-speed corners (i.e. most of them at Thruxton). But it’s not nailed down on rails like a race car. You’re still working at the wheel, staying on top of the car. You’re really driving it.

I start with stability control switched off but traction control on, assuming I’ll only need it out of the chicane at the end of the lap. But the TC light is winking in some fifth gear corners, over Thruxton’s bumps. There are some particularly wicked thumps through the quick Noble left-hander. It’s a case of hanging onto the wheel tightly, knowing that the GT3 will likewise cling to its line.

After a break, the tyres are swapped for stickier, more aggressive Cup 2 R tyres and I run with both ESP and TC disabled. Once there’s heat in them, the extra grip from the front is immediately apparent. Through the medium-speed complex of the Campbell, Cobb and Seagrave corners near the start of the lap, where you must wrestle the car right, left, right, the nose hits the apex more eagerly. 

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The rear follows obediently – and in some of the faster corners, there’s actually a fair bit of oversteer, because the front biting so much better. You need fast hands in some of the faster corners to stay on top of things but the Manthey reaches its limits in such a progressive way that it’s exciting rather than scary.

For occasional trackdays, a standard 992.2 GT3 is very much up to the task. Our previous tests on track at Valencia and the Nürburgring Nordschleife have proven it’s a cut above the vast majority of sports cars for both stamina and stability. But for track regulars who want more, the package brings more precision and ultimate ability without compromising what makes the GT3 great. 

Incidentally, the 992.2 Kit has recently knocked five seconds off the previous-generation Kit’s time around the Nordschleife, in the hands of reigning DTM champion Ayhancan Güven.

Price and rivals

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Some parts of the kit can be ordered separately but since the components have been designed to work in harmony together, Manthey describes the sum of the kit as being greater than the individual parts. For the first time, the kit can be ordered directly from the 911 GT3 configurator. The car cannot come delivered with it already fitted, however, due to homologation requirements, an official Porsche centre must apply the kit separately. In the UK, it’s priced at around £56,000 including VAT. You’ll also need a 992.2 GT3 for it to be fitted to, so make that approximately £214,000 for the car and the kit combined, plus a separate fee for the fitting itself. Each of the UK’s 47 centres is qualified to fit and service the kit, and replace parts with spares in the future. All the components carry Porsche part numbers and the kit comes with a full factory warranty.

Whilst it’s certainly not a small sum of money, there’s no questioning the extra ability it unlocks for those who need it. Whereas modifying older generations of 911 GT3 models could ordinarily devalue their worth on the used market, the Manthey kit’s Porsche-ratified and warrantied parts may make that less of an issue.

What could you have instead? Well, for not much more money, 992 GT3 RSs are around, now the absurd speculative bubble has deflated somewhat. Otherwise, apart from much more hardcore machinery like Ariel's Atom 4R, 

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