This paper proposes a modification to the Academic COSYSMO estimating relationship to remedy a critical limitation in its current implementation of the cost drivers. The effort multipliers defined for these drivers have an overdramatic impact on the nominal effort, which unrealistically amplifies or compresses the effort estimate. This problem severely limits its practical applications. The newly proposed parametric relationship is inspired by the COCOMO II modeling approach and based on the considerations of the life cycle impact of the cost drivers. Two additional cost drivers are also introduced. The feasibility of the new model definition is examined with a boundary analysis and validated by the analysis of historical data. This work is based on the practical implementation of COSYSMO at BAE Systems. In this paper, we present (1) an analysis of the problem with the current COSYSMO model definition; (2) a proposal of two new cost drivers added to the current fourteen cost drivers; (3) an analysis of life cycle impact of the cost drivers and a division of the drivers based on the impact; (4) the modified COSYSMO parametric relationship; (5) validation of the modified COSYSMO relationship through an analysis of historical data; and (6) conclusion and suggestion of future work.