Major exteriors changes were introduced in 1991.  New ground effects, rear spoiler, and hood were made standard on both the RS and Z28 (the IROC-Z was discontinued this year).  A new special service B4C package was introduced and made available to law enforcement, government, and military agencies.  The B4C was essentially an RS with the Z28 powertrain and suspension.  Just under 600 B4C units were sold.