The top of the Porsche Cayman, and now 718 Cayman, range has always been the GT4. And unlike the 911's GT3 and GT2 variants, it's never had a super hot RS variation. That may be about to change based on these spy shots.
It's very clear that this is a 718 Cayman GT4, and there are a number of features not found on the production car. In the hood, there are a pair of NACA air ducts. They look like the ones on the hood of the 911 GT2 RS, which feed cool air down to the brakes.
Around the sides, the Cayman's rear quarter glass has been replaced with louvered panels. The louvers are aimed so that they pull in air, perhaps for the engine intake or to feed bigger radiators.
Finally, at the back, we have the rear wing. It sits much higher than the one on the regular GT4. It also is a different shape than the GT4's wing. Don't look for those crazy supports on the production car, though. Those appear to be special prototype supports that accommodate multiple types of wings and different heights for different cars.
Since this GT4 RS is based on a current car, we're expecting to see it revealed in about a year. In addition to the aerodynamic upgrades, it should feature upgraded suspension and brakes. It will likely continue to use the naturally aspirated 4.0-liter flat-six from the regular GT4, but it should have more output than the 414 horsepower and 309 pound-feet of torque of the GT4. Expect a price tag above the GT4's $100,000, too.