 Dealer repairs of the Callaway Twin Turbo Corvettes were covered by the standard GM 12 mo./12,000 mile warranty, with Callaway Cars, Inc. reimbursing dealers for time and materials on repairs to the added components.This was the only time where GM has allowed a factory orderable non-GM performance enhancement on the Corvette.The ultimate Callaway Twin Turbo Corvette is known as the Sledgehammer Corvette.