Chevrolet decided to respond with a complete Regular Production Option ("RPO") package for the new year. Thus, a special 427 cubic inch version of the W-Series 409 engine was developed. It would use a stroked version of the venerable 409 and be used in the 1963 Chevrolet Impala Sport Coupe. This would be available and could be ordered under Chevrolet RPO number "Z11"