The performance of Gasoline Direct Injection (GDI) is governed by multiple physical processes such as the internal flow or the mixing of the liquid stream with the gaseous ambient environment. A detailed knowledge of these processes even for complex injectors is very important for improving the design and performance of combustion engines all the way to pollutant formation and emissions. However, many processes are still not completely understood, which is partly caused by their restricted experimental accessibility. Thus, high-fidelity simulations can be helpful to obtain further understanding of GDI injectors. In this work, advanced simulation and experimental methods are combined in order to study the spray characteristics within a 3-hole GDI injector in detail. In particular, the impact of cavitation and hydraulic flip on the atomization is analyzed. Coupled compressible Large-Eddy Simulations (LES) of the internal nozzle flow with and without cavitation model, Direct Numerical Simulations (DNS) of the resulting primary breakup, and particle-based far-field LES are performed in order to achieve a detailed data set of the injection process. X-ray measurements visualizing cavitation inside the nozzle and droplet size distributions in the far-field obtained by Phase Doppler Particle Analyzer (PDPA) measurements are used for validation. The evolution of near-nozzle droplet size distributions is shown and used to gain further understanding of the underlying breakup processes.