To meet the requirements of API 618 4th Edition, Design Approach 3, the vibration and stress levels in the compressor manifolds and piping must be calculated. Studies M.6 and M.7 are described. To date, many would insist that this type of analysis is impractical or ineffective. It is important to consider the appropriate dynamic forces when performing this type of analysis. However, this consideration is obviously not sufficient. An accurate model of compressor components, vessels and piping is vital. This paper not only demonstrates how these studies may be completed, but demonstrates that they can be valuable in the successful design of reciprocating compressor packages. Shop and field testing has been necessary to develop accurate techniques. Real life examples are presented to make the connection between the models and the compressors they represent.