"When we came up with the SPR1 concept, it was not our goal to make a 1,000hp car or go for ultimate top speed," Sportec's Uli Hodel explains. "Rather, we wanted to build a genuine 800-hp car that was civilized enough to use every day and also be finished to the highest standards both inside and out. The fact that we now have 858 hp just by improving efficiency is a bonus."

The increased efficiency has also changed the way power is delivered. With its stock 3,600cc capacity unchanged, the SPR1 made peak power at 8200 rpm with the cut-out at 8600. The more efficient SPR1M engine develops 858 hp at just 8020 rpm with the limiter at 8400 rpm in fourth gear and 8200 rpm in fifth and sixth with the stock final drive. Torque is 649 lb-ft at 4800 rpm.

The single-mass flywheel is mated to a beefy dual plate clutch, and the limited-slip differential was changed from the factory GT3 40/60 (acceleration/over-run) ratio to 60/40 for better turn-in. The gearbox internals have been beefed up using steel synchros, and all ratios are stock apart from a taller sixth gear, which runs the car to 395 km/h (245 mph) in still air on the flat. As the 802-hp SPR1 was officially clocked at 378 km/h (234.8 mph) on the banking at Nardo and later unofficially achieved 387 km/h (240 mph) at Papenburg, there's no reason this latest version should not exceed these numbers.

"Top speed is an interesting exercise," says Hodel. "But to be frank, there is no track open to the public where you can test that-and no autobahn straight long enough, either."

You cannot build cars at this level without input from world-class engineers; the company that built the roll cage also makes cages for the Mercedes-AMG DTM racecars. Similarly, one of the two men who designed and made the body components for the SPR1 was also involved with the bodywork for the Porsche GT3. The other is the famous Swiss designer, Franco Sbarro, who made the initial drawings and the performed the prototype modelling.

While the power increase with the trick Sportec engine is truly immense, this doesn't mean that weight loss was unimportant. The target was to trim at least 50kg from the weight of a stock GT3, and in the end the SPR1 tips the scales at 2,965 pounds including air conditioning and stereo.

The new front and rear bumpers, rear wings and rear spoiler are made from carbon fiber. The aluminum doors are the factory items as fitted to the Turbo and GT3 RS. It's always safer to use aluminum rather than carbon doors as they will not shatter upon impact in a crash. The SPR1 Club Sport version has carbon doors because it also has a full roll cage and five-point harnesses for track use.

The result is a car that looks like a normal 997 at first glance, but when you look more closely you realize that the shape and width of the rear quarters are different, while the bumpers and rear wing are also unique.

Satin gray Sportec seven-spoke forged alloy wheels really stand out against the white bodywork. These one-piece 9.0 and 12.5x20-inch wheels weigh just 19.8 and 25.6 pounds respectively, and are sized to fit under the wheel arches perfectly without spacers. The tires are 245/30 and 325/25 Michelin Pilot Sport 2s.

The front and rear suspension is partially Rose-jointed for more direct response, while the Club Sport version is fully Rose-jointed. The Bilstein active damping system, controlled by a Sportec ECU, is unique to this car. Using g-sensors to measure acceleration, braking, yaw, lateral forces and so on, the ECU compares inputs to known values and reacts accordingly.

"We can even program it so that the outside dampers stiffen up as you turn into a corner to reduce roll," says Sportec test driver Andreas Hodel. "Thus we could make the outside damper go stiffer in bounce with the inner going harder in rebound at the same time."

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