Porsche 911 GT3 RS Manthey kit review – the ultimate Nürburgring toy tested to the limit

Back in 2023, Porsche’s Andreas Preuninger and his team were worried they’d gone too far and made the 992 GT3 RS too track focused. However, on our 2023 Car of the Year test in cold, wet Scotland – on its Goodyear Eagle F1 SuperSport RS tyres – it was superb, not least for finding grip and dynamic balance where less sportily-tyred rivals struggled. Needless to say, on track it feels even more at home. What more could you want? 

The answer, according to Porsche and Manthey Racing, is the almost cartoonish GT3 RS with Manthey Racing kit. We’ve driven it extensively on road and track, even comparing it to the standard GT3 RS on the circuit at Anglesey. 

Something of a cult amongst fans of hardcore Porsches  Manthey, established in 1996 by successful Carrera Cup, DTM and VLN racer Olaf Manthey, is based in Meuspath, just a stone’s throw from the Nordschleife’s Döttinger Höhe straight. The team’s record in the N24 is the stuff of legend, its seven victories (all achieved with Porsche 911s) matched only by its arch rival, Audi-supported Phoenix Racing, who scored a seventh victory for the R8 LMS in 2024.

Porsche 911 GT3 RS with Manthey Racing kit – the key changes

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• 1000kg of downforce at 177mph (up from 860kg), but no extra drag
• Stiffer spring rates and revalved dampers, still with full adjustability
• Braided brake lines

To create the kit, Manthey concluded there was little scope with the engine, the fabulous, naturally aspirated flat-six having required much attention to meet stricter emissions standards and maintain its 518bhp output. 

Most would have concluded that there was little scope with the aero either, the front boot having been sacrificed for a centrally mounted radiator, allowing active aero. Proper stuff, with adjustable wing elements at the front and a DRS-style wing at the rear micro-managed in real time by a computer that knows just how much downforce the car can take. 

The package of components it has developed is extensive and increases downforce from 860 to 1000kg at 177mph without increasing drag. There’s a deeper front splitter and bigger rear diffuser, extra vanes on the trailing edge of the roof, that distinctive carbonfibre shark fin and massive rear-wing end plates, plus the rear-wheel covers, of course.

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Michael Grassl, sales director at Manthey Racing, explains that the carbon rear-wheel discs counteract the effect of the spokes of the upper half of the wheel rotating against the airflow and also help prevent air from the underfloor escaping via the wheel wells, improving the effect of the diffuser and the rear wing. 

The wing and bigger end plates were developed in CFD and proven in the wind tunnel, and the devil is in the detail. Look closely and you’ll spot a small vent in the lower portion of each end plate that releases a build-up of high pressure in the low-pressure zone.

There’s also a bite out of each trailing top corner that reduces turbulence – remember the visible rear-wing vortices of old F1 cars in the rain? Meanwhile, the shark fin, or sail, helps stability in high-speed corners and replaces the glass rear screen for a 25 per cent weight saving.

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In addition, the Manthey kit includes increased spring rates, up 30 per cent front, 15 rear, and new dampers with separate bump and rebound valving. They’re semi-active, controlling the ride height and adjusting the damping in 240 milliseconds, and the standard car’s configurability is retained, albeit with a Manthey flavour. The final part of the kit is braided brake hoses. Total price of the conversion? A cool £100k.

These Manthey ‘Kits’ have been available through Porsche’s Tequipment option catalogue since May 2021. We sampled a 992 GT3 fitted with a full Manthey package when it starred in our 2024 Track Car of the Year test (with a new 992.2 Manthey kit now out that we’ve also sampled). 

Surprisingly different from the stock GT3 in character and capability, this hardcore take on a familiar Flacht favourite whetted our appetite for what was then Manthey’s very much in-development GT3 RS prototype – a YouTube sensation after a heavily camouflaged and outrageously bewinged car was spotted undergoing testing on the Nürburgring Nordschleife.

Porsche 911 GT3 RS MR on track at Monza – John Barker

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I may be a Monza newbie, but on my third ever flying lap at ‘The Temple of Speed’ I arrive at the first chicane at about 150mph and bury the brake pedal at the 200m board. The car sheds over 100mph confidently, we snick through the chicane, and the eager flat-six begins building up speed again.

This morning I wouldn’t have predicted this turn of events, but I’m putting my faith in Porsche track instructor Florin Sutterlin, who’s setting the pace in an identical 992 GT3 RS. In a few laps’ time I’ll swap to the car I’m actually here to sample, the remarkable Manthey Racing 911 GT3 RS MR.

After eight or nine intense laps in the standard GT3 RS, we pull back into the pits and a couple of minutes later I’m trundling down the pitlane in the Manthey RS, selecting Track mode once again. On the short run to the first chicane it feels like rejoining a race after a pit stop, being dive-bombed by a variety of Porsches hauling down from sixth to second gear. A lap and a half later, the tyres of the MR RS – Cup 2 Rs rather than Cup 2s – are warmed up and we are back on it.

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A couple of flying laps in and I notice that the MR feels a little more settled than the RS in the Varianti Ascari, so I can get on the throttle a fraction earlier with the result that I’m starting to gain on Florin and having to feather the throttle before the brake point. It’s the same into Parabolica and on the start straight. Also, the MR feels very settled through the more open Lesmo 2, slicing across the cuttable inside kerb.

In other respects, the MR feels like the stock RS. Monza is brutal on the brakes but both cars just keep on hitting their brake points, keep finding cornering grip and traction. After half an hour, the only thing that’s feeling the strain is my aching back. I should have bought a HANS device so I could use the full harness belt. 

Then I notice a puff of smoke from the right rear of Florin’s GT3. And another. Then a brief orange spark of flame. I flash my lights, back off a bit and we both peel off. In the paddock he’s quite unconcerned, explaining that rubber debris occasionally gets flicked up and briefly ignited on the hot exhaust. 

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Does the GT3 RS go quicker with the MR kit? I’m not sure if it’s the kit or the stickier Cup 2 R tyres or me getting more confident. Or a combo of all three. I’m also not convinced that Monza is the best place to demonstrate the advantages of the kit; it’s all so smooth and the standard car is easily flat and solidly planted right through Curva Grande, so the additional stability of the shark fin doesn’t tell through there.

I’m not sure around Monza I could positively identify the performance uplift. Maybe that’s just me, or perhaps the Nordschleife’s bumpy braking zones would better show off its damping, and Silverstone’s Copse, Stowe or Becketts complex would better demonstrate its high-speed aerodynamic stability – certainly on the Nürburgring, the changes are worthwhile, with Porsche publishing a 6:45.389, some four seconds quicker than the standard car.

The standard car is so good on road and track, finding any gains requires real ingenuity, solutions that almost defy physics, and even if you get there, you still have the law of diminishing returns to contend with. That said, I reckon the Manthey kit is going to make a lot more sense on the upcoming, 750bhp-plus GT2 RS.

Porsche 911 GT3 RS Manthey Racing kit v standard GT3 RS – Richard Meaden

‘To help get dialled in to the Manthey RS, we first do a timed run with a new set of Cup 2s rather than the more extreme 2 Rs. It’s a worthwhile exercise. Not least because the resulting best of 1.11:10 eclipses the stock RS time by a whisker (8/100ths to be precise). More valuable is knowing that the additional downforce, needle-sharp front-end, resolutely planted rear-end and bulletproof brakes match the best efforts of a standard RS shod with Michelin’s grippiest road-legal rubber, apparently without being any trickier to drive.

> Read the full GT3 RS: Manthey v standard track battle feature here

‘Pressure ramps up when we swap the Manthey car onto Cup 2 Rs, which only give their absolute best for one or maybe two attacking laps before stabilising a few tenths off their maximum performance. As Manthey technicians had the tyres on warmers, the out lap needs to be just quick enough to maintain the heat but not so quick as to waste any of that peak performance.

‘The fast laps on Rs are even more special. The directness of the steering is now even more intense, with endless bite and immediate response to the smallest of inputs. It’s this confidence in the front-end that gives you the foundation upon which to build the lap, braking even deeper and steeling yourself to come off the brakes and roll as much speed as possible into the apex before trying to be just as decisive when you get back on the power.

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‘Much like the faster turns, the Manthey RS cuts through the tighter corners that bit more cleanly, allowing you to carry small but meaningful gains to the apex then get better drive out onto the straights. Another advantage is increased composure on the few occasions you can take some kerb, Manthey’s bespoke controller for the PASM monitoring and adjusting the damping of each wheel in real time, with special attention paid to managing vertical wheel movement over sharp impacts.

‘Crossing the line to complete the final flying lap, the Vbox shows a best of 1:09.9, with the other laps within a tenth or three. That’s a 1.3-second improvement over the standard RS around a 1.55-mile lap. I have no doubt that with further laps (and fresh tyres) further improvements could be found. Not huge, but maybe half a second. 

‘Not everyone will see the point, but for those who do, few cars at any price deliver this kind of experience, one which immerses you in the addictive process of extracting more from yourself to get the most from your car. Perhaps the biggest testament to what the Manthey Kit achieves is the fact that this 500bhp Porsche 911 is a tenth of a second faster than Ferrari’s 1000bhp, SF90 Assetto Fiorano, and second only to the ultra-specialised single-seater BAC Mono 2.5 in our leaderboard of all-time fastest street-legal cars.’

Porsche 911 GT3 RS MR on the road – Richard Meaden

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The general cockpit vibe is little changed from the regular car. Unsurprising given that it remains stock apart from Manthey kickplates on the sills. The biggest change comes from the replacement of the rear screen glass with a 25 per cent lighter carbon panel that serves as the support for the dramatic shark fin. Rearward vision was never great in an RS thanks to the wing, but only having the door mirrors to see behind you does feel more restricted. This car’s owner intends to install a rear-facing camera, which would be a neat solution.

The effect the Manthey RS has on others is not to be underestimated. Slack-jawed gawps are par for the course. Pedestrians rotate their heads like owls. Other drivers seem slightly bemused, as though a racing car has just joined them on their commute. Phone cameras track your every move. If you like making discreet progress, this car is not for you. But then, to be fair, neither was the standard 992 RS. 

The regular car’s configurability remains intact, with suspension, limited-slip diff, stability control and DRS controlled via the same neat array of rotary switches on the steering wheel. Comfort is definitely the least combative setting, but there’s still an uncompromising, fist-like tightness to the damping that sets the tone for an all-consuming experience. Manthey’s mantra is heightened steering response combined with stability, which is exactly what you want around the Nordschleife but not necessarily so crucial on the B660.

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It comes as a shock to discover just how responsive the steering is to your inputs. The same goes for the brakes, which have epic pedal feel thanks to new pad compounds plus steel braided brake-lines that reduce line expansion under pressure.

At first you fear the rear has no chance of living with such lightning responses, especially at lower speeds when the wings aren’t working the air so hard, but once you get beyond the unnerving rate of turn-in you find the steering is incredibly accurate and the tail beautifully in-sync and blessed with exceptional traction and lateral grip.

> Porsche 911 GT3 Manthey Racing v Spartan: £200,000 track toys battle it out

The blend is compelling. British A- and B-roads are not the Manthey RS’s natural habitat – that is undoubtedly the incomparable Nürburgring Nordschleife – but it bosses street use in its own way. You have a car that genuinely feels like it is connected to you via nerve synapses. I’ve never driven anything quite like it.

It’s worth noting that you can perceive some of the aerodynamic benefits on the road, and also appreciate how they work in harmony with the chassis modifications. Find an empty stretch of dual carriageway, pick your speed and make some lane-change manoeuvres and the Manthey RS feels uncannily planted. No slack, no hesitation, just scalpel-sharp turns. Like skiing with freshly sharpened edges.

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In a nutshell, the faster you go, the better this car feels. Both in terms of how it settles into its damping, and how the downforce supports those dizzying responses by giving you growing confidence in being able to lean on both ends of the car. Even the DRS is more pronounced, a nudge of the steering-wheel button noticeably freeing the RS. Imagine finding you’ve been driving with the handbrake clicked on a notch and then releasing it, and you’ll get the idea. (And yes, I know this requires you to be old enough to remember the days of handbrake levers and not buttons.)

For some, the Nürburgring Nordschleife and the obsession it inspires is beyond comprehension. The Manthey RS is not for them. A truly hardcore machine conceived and executed with a racing mindset, it goes to such extremes that only those who crave the absolute peak of street-legal performance on track – something the factory 992 RS arguably delivered already – will accept the compromises and truly ‘get’ what it’s about.

Yes, it comes at the expense of ride quality and takes the looks to extremes some won’t wish to go to. Yet hardcore though it is, the Manthey Kit doesn’t ruin the RS for road use.

Manthey Racing Porsche 911 GT3 RS specs

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