RENNtech is considered the premier Mercedes-Benz specialist and Hartmut Feyhl himself is regarded by many as USA's foremost authority in Mercedes tuning. His vast experience comes from 12 years spent at AMG Germany before serving as the North American division's Technical Director. Prior to the tuning company's merger with Mercedes-Benz in 1989, by the request of AMG Germany, Feyhl branched out on his own to start RENNtech and service the existing AMG North America customers.

This RENNtech R3 Performance package transforms the 2021 AMG GT Black Series into the world's most powerful street-legal AMG, boasting an astounding 1,066 horsepower and 831 lb-ft of torque. This upgrade significantly boosts performance, achieving up to 938 WHP and 731 WTQ on RENNtech's DYNO, with peak gains of +321 HP and +185 LB-FT in the critical 5,500-7,000 RPM range. The package includes RENNtech Stage II turbos with larger, lightweight forged billet wheels, optimized ECU+ programming, stainless steel downpipes, a TCU tune, performance clutch, and BMC air filters. These enhancements not only increase power but also improve throttle response and reduce turbo lag, all while running on standard 93 octane fuel for convenience in both track and street driving.

• 1066 HP with ECU Upgrade
• Stainless Steel Downpipes with 200 Cell Cats
• BOV Adapters
• Stage II Turbo Upgrade
• Upgraded Racing Clutch
• TCU Upgrade
• Renntech Track Series Forged Wheels
• Carbon Fibre Bumperette Delete
• Satin Black Wrap with Orange Details
• Carbon Fibre Wheel Extractors
• Miles 7580, per owner