In mid-1970 Buick made the GSX tuning kit available for the Grand Sport 455, which included front and rear spoilers, two exterior mirrors, G60x15 tires on 7 "wheels, front disc brakes, reinforced suspension and black vinyl bucket seats. The sportier version had a 360 horsepower engine, also available on the Grand Sport with the Stage-1 kit. The examples produced with the GSX kit were a few hundred. Production went on until 1972.