The Porsche 911 GT3 RS is a benchmark in its class as one of the best road-legal, track-focused vehicles on the market. In fact, with some adjustments from the experts at Manthey Racing, the existing model is even quicker than the 1,250-horsepower Chevrolet Corvette ZR1X, despite the 'Vette having more than twice the power.Porsche is slowly introducing the refreshed 911 lineup, which goes by the internal code 992.2. The updated Carrera 4S, Cabriolet, Targa, Turbo, and more are already here, but we're still waiting for the revised GT3 RS. A new batch of spy photos shows a pair of them during testing. One is in the usual black body covering that Porsche uses when developing vehicles. The other wears a camouflage wrap, which is unusual for a test car from the brand. A Look At The Refreshed GT3 RS CarBuzz/ValnetThe 911 GT3 RS refresh doesn't overhaul the existing model, but it has some obvious changes. In front, there's a new front fascia with a more complex design. It includes a central opening with a smaller inlet in the center and a pair of uprights. There are also big openings on the outer sides. Big openings on the hood and vents above the front fenders are still present.The two cars in these spy shots are slightly different. The one in the camouflaged wrap has canards at the outer corners and appears to have a more prominent splitter than the black car. The tweaks might be part of the optional Weissach Package, which adds track-focused components to the GT3 RS to cut its lap times.In profile, the refreshed GT3 RS doesn't look much different from the current one. The vehicle still looks like a track car for the street, especially with the bulging fenders and massive rear wing.At the back, the all-black car still has a placeholder panel over the bumper, but the camouflaged vehicle reveals more of the design. There's a new opening on the back panel, and given its location, the hole is possibly for extracting more heat from the engine bay. There are also redesigned vents behind the fenders. A diffuser with prominent vanes is still an eye-catching element on the tail. A New Engine That Purists Won't Like... Maybe CarBuzz/ValnetPorsche has been testing the refreshed 911 GT3 RS for quite a while. A recent rumor suggests that the company might be preparing a major engine change. The report indicates that the car might adopt a turbocharged powerplant, which would be revolutionary for the model. Traditionally, the GT3 RS has been the brand's ultimate naturally aspirated 911, while the GT2 and GT2 RS have been the top turbocharged versions.The existing 911 GT3 makes 518 horsepower from its 4.0-liter flat-six engine. Making over 100 hp per liter is impressive enough from a naturally aspirated powerplant, and Porsche blasts past that benchmark with a mill producing 129.5 hp per liter. However, there are limits to what an engine can produce without resorting to increased displacement, forced induction, or electrical assistance. The automaker might be near the limit of what the current mill can offer while still being road-legal. CarBuzz Insight – Why This Matters: CarBuzz/ValnetThe Porsche 911 GT3 RS is one of the most exciting cars on the market and shows the brand's engineering skill at its finest. Significant updates to it are a big deal. Judging from these photos, the engineers aren't making significant exterior changes to the model, but the team can only do so much to improve the performance out of the car's basic shape.Porsche does a great job of keeping its work secret, but we hope that the brand sticks by a naturally aspirated powerplant for the updated GT3 RS. In an era when many performance engines use forced induction or hybridization, there's something very special about a world-beating model using purely combustion power.porsche-gt3-rs-2