Before the impossibly expensive Mercedes-AMG One, the AMG GT 63 S 4MATIC+ E Performance is the most powerful road-legal AMG. This alphanumeric soup of a four-door plug-in coupe makes electrified 831 horsepower (620 kilowatts) and 1,033 pound-feet (1,400 Newton-meters) of torque in stock form.

But unlike the complicated AMG One hypercar, which needs an engine rebuild after every 50,000 kilometers (about 31,000 miles), the AMG GT 63 S E Performance can receive aftermarket tuning.

Case in point: Opus presenting its stage 1 performance tuning of the PHEV.

The Nurburgring-based tuner upgrades the AMG GT 63 S E Performance, allowing the electrified model to churn out up to 952 hp (710 kW) and 1,143 lb-ft (1,550 Nm) of electronically limited torque. The electronic unit contributes 204 hp (152 kW) to that, while the 4.0-liter M177LS2 V8 makes 748 hp (558 kW).

Of course, these numbers translate to exhilarating performance. Opus claimed a sprint to the centenary mark (62 miles per hour) in just 2.7 seconds from a complete standstill – a tad quicker than the production model. The 200 km/h (128 mph) mark is reachable in 8.55 seconds, which is a second quicker than in stock form.

The tuned version is also fast. Opus tested the tuned AMG GT 63 S E Performance on the Autobahn and was able to clock in 321 km/h (199 mph), which you can watch through the video embedded atop this page.

The Opus-tuned AMG GT 63 S E Performance will be available for purchase in October 2022 after it receives its TUV approval. The company also offers a special exhaust flap control system and an OBD lowering module. In winter, Opus said that it will try to break the 1,000-hp barrier, though the tuner admits that it will be challenging as compared to non-hybrid AMGs.

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