The Sport Coupe model was replaced by the RS model in 1989.  The RS gained the ground effects popular on the IROC-Z and Z28 from previous third-generation years.  The IROC-Z was available with a 170 hp TPI 305 V8, a 215 hp TPI 250 V8, or a new-for-1989 240 hp 350 TPI V8 (although it was only available with an automatic). Some people liked the simpler design that the sport coupe had , but the RS ground effects pleased many people.