Nowadays, the automotive industry is increasingly facing of reducing vibration & noise in the vehicle. More particularly on the engine area, the development of fuel components based on high pressure pumps, rails, any pipes and injectors are a subject of a particular NVH attention. The use of modern digital techniques such as 3D finite element vibroacoustic, leads to use virtual prototyping as complementary to traditional real hardware prototypes development. Among interest, number of iterative loops to reach a best design brings an important value to new product development with an optimized cost. Basically the core part of virtual prototyping is about 3D finite element models for each component. It is quite challenging to establish these models, as they must mimic the entire physical phenomenon of real structure borne hardwares sound in the whole audible frequency range. Several items allow bringing the most appropriate digital model for NVH study, such as experimental data for correlation, definition of source of loads and definition of boundary conditions. Limitations of models are also identified and allow opening 1 true question: Should we stay considering only each component separately or as an assembly of parts of a larger system in the development process? In the proposed paper, a stepwise method is going to be reviewed based on 3D FEM Vibro-acoustic to support virtual NVH prototyping. It leads designing real products. A particular focus on examples based on High pressure pumps and SCR air cooling injectors are reported there.