Modal decomposition is a popular analysis approach involving the description of a target system via a bank of resonant oscillators called modes. Early sound synthesis frameworks successfully exploited this idea for the simulation of vibrating objects such as bars, plates and strings. While popular, modal synthesis is often applied to linear systems, since the modes become densely coupled in systems presenting distributed or multiple nonlinearities. In this work, the modal approach is used for the simulation of nonlinearly connected systems. When the nonlinearity is of cubic type, a suitable energy-stable modal update can be derived requiring the solution of a single linear system at each time step. A working plugin written in the C++ programming language is presented. Moreover, the performance of the plugin is analysed considering systems of different dimensions, defining the current limits for a real-time application of these models. The analysis also revealed a linear correlation between the number of modes which compose the systems and the CPU usage necessary for their real-time computation.