The C4 Chevrolet Corvette was a capable sports car, but for those seeking an additional boost in performance, Callaway Cars was able to offer a range of performance-enhancing packages starting in 1987. The most well-known offering was the Twin-Turbo, which was available as a factory option, but with work done by Callaway (RPO B2K). Other notable creations by Callaway included the Speedster, Supernatural, and the heavily tuned Sledgehammer, which for a period of time was the fastest car in the world.