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When Chevrolet changed gears to the LT1 engine, Callaway revealed their new SuperNatural line and the CR1 based on the ZR1’s LT5. Options for the CR1 included the radical Aerobody, German upholstery and special wheels, brakes and exhausts. The CR1 used a larger displacement to produce either 475 or 490 bhp.
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.
The Corvette C5-R was part of a plan by General Motors and their Chevrolet brand to create a factory team to participate in grand touring races not only in North America, but also elsewhere in the world, most notably at the 24 Hours of Le Mans. GM had previously been against approving factory support for Corvette racing programs, although the IMSA GT Championship's Corvette GTPs had seen some support until they ended competition in 1989.
For the fourth generation Corvette, legendary Corvette racer John Greenwood developed the G4R. It was essentially a radical bodykit that usually followed a high level of performance upgrades. Included was a ground effects package that had integrated lights on the front valance. Furthermore the a new engine scoop and rear wing were fitted.