You might think the Porsche Cayman GT4 RS, with its screaming 911 GT3-derived engine and 9,000 rpm redline, is the pinnacle of Cayman performance. But there’s another level for those who crave even more track-focused insanity: the GT4 RS Manthey. Built to sacrifice whatever road manners the GT4 RS might have had, this is a no-compromise, lap-time-chasing machine.
For those unfamiliar, Manthey Racing is a German race team with a storied history, including running Porsche’s GT programs. Porsche owns a controlling stake in Manthey, and since 2021, the team has been producing track-honed performance kits for Porsche’s lineup. These kits, available through certified Porsche dealers, are designed solely to enhance track performance.
The GT4 RS is already a monster. With a 493-horsepower engine pulled straight from the 911 GT3, massive brakes, and aerodynamic tweaks, it’s as close as Porsche will let the Cayman get to the 911. But Manthey Racing wasn’t satisfied. Their kit focuses on refining the car’s cornering ability and braking stability, without touching the already powerful drivetrain.
The Manthey GT4 RS sports a larger rear wing, carbon aero blades over the rear wheels, and steel-braided brake lines. It ditches Porsche’s adaptive suspension for manually adjustable coilovers, a move that strips away any semblance of street comfort. The result? A car that’s stiffer and even more focused on the track. If you’re buying the Manthey kit just to show off at your local cars and coffee, you’re wasting your money.
We took the Manthey-equipped GT4 RS to Lime Rock Park, a short but technical track in Connecticut, to see what all that money—$53,946 plus installation—really buys you. At first, it’s hard to detect any major differences from the standard GT4 RS. It sounds just as glorious, with the same induction roar, and initially feels just as balanced. But when you start pushing, the advantages of the Manthey kit become clear.
The braking performance is especially noticeable. On Lime Rock’s front straight, the regular GT4 RS felt twitchy under hard braking. With the Manthey kit, there’s more initial bite and much better stability, likely thanks to the increased downforce. The Manthey car feels more planted and confident, transforming braking zones into opportunities rather than nerve-wracking experiences.
The cornering is sharper, too. There’s a slight increase in understeer, but it adds stability, making the car more predictable and easier to control on the limit. On faster corners, like Lime Rock’s West Bend and Downhill, the additional downforce shines, allowing you to carry more speed with confidence.
So, how much faster is it? After two timed laps, the Manthey GT4 RS clocked a 58.47-second lap, half a second quicker than the non-Manthey version. That might not sound like much, but remember, Lime Rock is only 1.5 miles long. On larger tracks like Spa or the Nurburgring, that gap would likely widen. In fact, on the Nurburgring, the Manthey car shaved six seconds off the standard GT4 RS’s time.
But here’s the big question: Is it worth the nearly $54,000 price tag? If you’re just looking to enjoy occasional track days and aren’t obsessed with shaving tenths off your lap time, probably not. The GT4 RS is already an incredible machine in its stock form. But if you’ve got the money and are determined to have the absolute best track version of the GT4 RS, the Manthey kit is a must-have.
And for those who just want to look cool, Porsche will sell you Manthey’s aero wheel blades for $680.
