In 1979 a 935 K3 was the overall winner of the 24h of Le Mans. A “normal” 935 came second and a 935 K2 came third overall. So it was an impressive car even back then.
What are the differences between a K3 and a regular 935? They’re much different: the engine has two turbos, the suspension is modified, it has bigger brakes and a reversed “upside-down” type gearbox in order to let the titanium axles work straight and lower the CG, and different bodywork and aerodynamics. In the end, the 935 K3s were basically a new 935 model made by Kremer to keep these cars up to date as Porsche stopped making them because they had so much power they bent the chassis! Oddly, Porsche featured K3s that were not factory-built for their official posters and press releases!