The range-topping 911 gets a twin-turbocharged 3.8-liter flat-six.

The rumors were true: Porsche is working on a successor to the 911 GT2 RS. The Stuttgart-based company has released the first official details about its upcoming high-performance flagship.

The GT2 RS benefits from an evolution of the Turbo S model's turbocharged 3.8-liter flat-six engine. Applying lessons learned on the track, Porsche's GT division added two bigger turbos tweaked to provide more boost, a model-specific exhaust that's much lighter, and stronger internal components.

British magazine Evo has learned the GT2 RS will receive a water-injection system that reduces intake temperature. Similar to what's offered on the BMW M4 GTS, the water-injection system bumps the flat-six's power output while improving efficiency and reducing wear on key components.

The GT2 RS is still at the prototype stage so final specifications aren't available yet. However, we know the six will send over 641 horsepower and 553 pound-feet of torque to the rear wheels via a dual-clutch automatic transmission. Porsche promises a zero-to-62-mph time of under three seconds.

"It's not just a chipped Turbo S, definitely not. It's a completely re-engineered car," said Porsche GT project director Andreas Preuninger in an interview with Evo. "[It's] a lot easier to drive than a 997 GT2 RS, which was a brute, to the point where you couldn't handle it sometimes," he added.

To save weight, Porsche has removed some of the sound-deadening material and replaced the glass with thinner Gorilla Glass. Buyers who want an even lighter car will be able to order the optional Weissach Package, which bundles magnesium wheels, a titanium roll cage, and a carbon fiber roof, among other go-fast goodies.

Porsche will begin pre-production of the 911 GT2 RS in the coming weeks, meaning the series-produced car is likely at least a few months away from hitting showrooms. We could see it this fall at the Frankfurt Auto Show, or at next year's Geneva Auto Show. Either way, it will land as a limited-edition model priced at over $200,000.

Photo credit: Evo.