Upgrades to the previous-gen 911 GT3 RS MR included KW coilovers, brake pads and lines, carbon parts, a rear wing, side skirts with air-guided elements, and magnesium wheels. Expect most of these features to make their way onto the latest iteration, improving the overall track performance.
The engine will likely be untouched since Manthey Racing focuses mainly on aerodynamic kits. The MR version will probably still be powered by a 4.0-liter naturally-aspirated flat-six engine, producing 518 horsepower and 342 lb-ft of torque. The standard car famously has new, hotter camshafts that help the vehicle achieve a boost in power from 6,000-9,000 rpm, which means you only reach peak power when you hit the redline.