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Offered from 1987 to 1991, the RPO-B2K upgrade was available from any Chevrolet dealer and also Callaway’s first major Corvette tuning program. Together, GM and Callaway made the upgrade package a Regular Production Order (RPO) which was the first time GM had outsourced such an option to a specialist manufacturer. It even had a factory back warranty. As the C4 updated, so did Callway’s program and by 1988, the B2K was pushing 382 bhp and 562 ft. lbs. of torque.
Chevrolet's introduction of the LT1 in 1992 as the base engine in the Corvette phased out the L98 based Callaway Twin Turbo. Previously, Callaway Corvettes made their increased power through positive manifold pressure; now they made it through increased displacement and finesse. Initially called the CL1 or CR1, they designated the chassis they were built upon. They were based on the pushrod LT1 cars (CL1) or the 32 valve DOHC LT5 ZR-1 cars (CR1).
Genovation GXE C7 Corvette Stingray
Genovation Cars unveiled an electric Corvette with more power under its hood than a Dodge Challenger Hellcat. They call their car the Genovation GXE, and it is an EV (electric vehicle) variant of the seventh-generation Corvette. The company decided that they would replace the factory LT1 engine found in all base-model C7 Corvettes with a pair of electric motors that, when working in conjunction with each other, provide over 800 horsepower and 700 pound-feet of torque. 
For the 2014 model year, the Chevrolet team sculpted the seventh-generation Corvette into the most sophisticated, most feature-packed Corvette produced to date. Facing a daunting challenge, new technology enabled Callaway engineers to produce breathtaking power with seamless transition into and out of positive manifold pressure. Entirely new, Callaway’s patented GenThree supercharger design improved airflow quality and increased charge air cooling capacity.
To understand why the Guldstrand GS-90 coupe and convertible differ so much, keep in mind that during the course of the C4 development cycle, no ZR-1 convertibles were planned, so the base C4 convertible had to be used in building a GS-90 Nassau Roadster, as it was called. The coupe, however, had the advantage of using the ZR-1 platform right from the get-go.