2025 Manthey Porsche 911 GT3 RS | PH Review

It feels like the world has gone bananas when there exists something called a Performance Kit that adds no more power or torque to the base car – yet costs £100,000. But when the base car in question is the 911 GT3 RS and the maker of said Performance Kit is Manthey, a little bit of clarity emerges. An options spend totalling tens of thousands is all too familiar on any stripe of 911, and if any outfit is going to make the greatest GT3 even better with no more horsepower, it’s the company that excels at making 911 race cars. A six-figure sum to make a sub-seven car that bit faster at the Nurburgring (expect a lap time soon) probably sounds nonsensical to most. Maybe it is. But since when did cars and options always have to make sense to everyone?

For your £99,999, Manthey customers will get new semi-active dampers, an assortment of aero bits (including the wheel discs, carbon rear window, shark fin like a 963 and preposterous rear wing), racier pads and six additional roof fins. With Porsche owning a majority stake in Manthey, too, it’s easier to get hold of than ever before. It can be ordered through your OPC, who presumably will only be too happy to see you again.

It also means access to Manthey cars on Porsche Track Experience days, as we were fortunate enough to experience at Monza. With prior experience of the car at the track, plus the chance to drive ‘standard’ GT3 RS against Manthey machine, it’s about as in-depth a comparison as we could ever hope to achieve. Never say PH doesn’t do insightful consumer advice. 

Here’s another top tip: bring your A-game to a Porsche Track Experience day. They don’t really suffer fools. Overtaking is either side at any time deemed safe, flashing a slower car to move gets a mention in the briefing (!), and there’s a warning about not getting too close to the downforcey cars down straights. Because they’ll brake even better than you can. If you’re grown up enough to be here, the assumption is that your driving will be as well.  

It’s all a bit intimidating, frankly, and when the time comes to drive a standard Weissach RS in the afternoon, Monza feels like a proper bear pit. Even in a road car stint, everyone is fired up and taking no prisoners. Instinct is to dive out of the way as a pack of GT3s descends like hungry wolves – say what you want about the GT3 market, these boys and girls can drive. But then we’re told to hurry up, dropping too far behind the pace car. Braking points are far too timid, apexes approached rather than properly embraced, and the initial exchanges as vivid as they are slightly disappointing.

If you can’t beat ’em, join ’em. With a bit more faith that, yes, the brakes can really be applied that late and that, yes, it really is flat through there, the experience is transformed. The RS is back to being its usual phenomenal self, and in a couple of clear minutes it’s totally absorbing all over again: ruthlessly composed yet minutely adjustable, engaging yet accommodating, tech laden yet richly rewarding. With power from that searing flat-six, mated to a sequential-spec PDK. There are more powerful track cars out there, but it’s hard to think of any better suited to the task. 

Well, apart from one, of course. It’s hard to swap straight from standard to Manthey, for the simple fact that you want to point and gawp at the new car for a good few minutes. To think that a 911 like this could be legally driven on a UK road is gloriously daft. Even in a paddock rammed with Porsche GT cars, the Manthey looks absurd in the very best way possible. Because you know that the strakes, the endplates the size of a TV screen and a carbon slab instead of a rear window are all for go, not just show. That it looks like something from a Marvel movie is just a fortunate coincidence. Honestly, the Performance Kit is truly bonkers, enough to make the actual race cars in attendance look a bit tame. It’s as serious as it is silly. But since when was silly a bad thing? As alluded to in the comments of the news story, best not be a slow coach with this sort of look.

While little has changed inside the GT3 RS, it doesn’t take long to identify some changes on the circuit. The brake pedal feel is even firmer, for starters, probably a little less immediate than stock though happier right in the meat of the travel. An upgrade to R-spec tyres from the standard Michelin Cup 2 offers all the benefits associated with better rubber on track, too. Turn-in is even more immediate, there’s a touch more weight to the wheel, and they must help the braking distance also. Plus, y’know, even more grip in a GT3 RS. 

Monza is the perfect place to show off what a Manthey-overhauled car is capable of. While nobody is cornering at 177 mph (where the tonne of downforce is produced, up from 850kg), it’s even flatter, calmer and faster through the quick stuff than standard. Very recent memory suggests as much, backed up by an ability to keep really close to a hardworking hot shoe up front that wasn’t possible previously.  Even Jörg Bergmeister reckons the Manthey “dives, pitches and rolls even less, offering a much more stable aerodynamic platform.” So while it’s nice to think that it’s confidence, familiarity and bravery contributing to the performance improvement, the 911 is doing much more of the heavy lifting. 

The Manthey totally redefines what should be possible in a roadgoing 911. Perhaps in a roadgoing car, full stop. It will accept – it relishes, in fact – full throttle at points that seem ludicrous, it absorbs kerbs like they’re mere petals littering the surface, and never seems remotely close to relinquishing any kind of purpose. The braking is out of this world, the ability both to shed so much speed and retain such unflappable poise is like little else. 

It says much that the stop into the first chicane, from something like 170 mph to about 30, feels no more taxing for the car than an amber traffic light coming at just the wrong time. You’ve never left leg pressed so hard in your life, but the pedal is endlessly reassuring right into the ABS. And the 911 never even thinks about deviating from its line, or showing any mind to imperfections. For a street car, it’s extraordinary.

The traction and the grip of the Manthey really are impregnable, meaning you exit bends even more violently – which makes a car of equal performance feel more accelerative still.  Watching a standard RS claw through Parabolica as you’re carving a flawless and unflustered (well, flawless enough) line around is an experience like no other. At a pace and commitment level that feels closer to out-and-out motorsport than a mere track day, the Manthey car is staggering; there’s proper GT3 machinery of not that long ago that doesn’t feel as suited to circuits as this. It’s formidably capable, yet remains utterly enthralling as well, not least thanks to that flawless powertrain, never happier than piercing your skull at 9,000rpm or banging in downshifts seemingly quicker than your finger can flick the paddle. Forget Longtails and Speciales and Super Trofeos. This thing is on another level. 

Hand on heart, though, it’s not a level that feels incredibly distant from the one occupied by a standard car. A Manthey GT3 RS is tangibly improved (you know that lap time will be wild) over standard around a track. All the incredible sensations felt are heightened, before even thinking about the jaw-dropping appearance. But there’s no escaping the £100,000 bit; this isn’t a seven-figure one-off where another £100k here or there doesn’t really matter. Even at secondhand prices, it’s another third on top of a GT3 RS. 

But then some folk spend way more than the purchase price on track projects, so probably it’s a moot point. Just to be seen in one might be enough for most – imagine this in Speed Yellow, for example. Tragically dull though it will sound after such exhilaration, our £100k would go on Cup 2Rs, those brake pads, and a whole lot of tuition. If only to stave off the headlight flash of an incoming Manthey for just a little bit longer. 

Engine: 3,996cc, flat-six
Transmission: 7-speed dual-clutch auto, rear-wheel drive
Power (hp): 525@8,500rpm
Torque (lb ft): 343@6,300rpm
0-62 mph: 3.2 seconds
Top speed: 184 mph
Weight: 1,450kg (DIN)
MPG: 21.1 (WLTP)
CO2: 305 g/km (WLTP)
Price: £192,600 (standard non-Weissach GT3 RS. Manthey Performance Kit £99,999.00)