Given the current level of computational resources that are readily available, three dimensional (3-D) gas turbine engine performance simulation remains extremely time consuming. The current paper presents a synthesis of existing flow simulation methods coupled together in the form of a new software package. The software is able to assess the impact of a 3-D flow profile at the intake inlet on engine performance, demanding relatively low computational resources. More precisely four flow simulation techniques are employed, represented respectively by four individual stand alone software sub-modules. 3-D Vortex Lattice Method (VLM) is used to simulate the intake flow. Subsequently the intake outlet 3-D flow profile is decomposed into a radial and a circumferential component. For the compressor performance simulation, that receives those components as inlet boundary conditions, a two dimensional (2-D) Streamline Curvature (SLC) simulation method coupled with an extended parallel compressor model is used. SLC addresses the impact of the radial flow distortion, whereas the extended parallel compressor model examines the impact of circumferential flow distortion on engine performance. The results of the above analysis are stored into an intake-compressor performance characteristic map, which is then fed into a zero dimensional (0-D) performance simulation tool in order to evaluate the overall impact of the intake inlet distorted flow on engine performance. The paper is divided into two major sections. The first one presents the individual flow simulation techniques, together with the corresponding software modules. A short summary of each method is given first and then the software module is described, followed by brief comments on the validation results that have been already published. The section in concluded by the description of the synthesized software. The second major section deals with the application of the synthesized simulation method on a turbojet engine. A generic turbojet engine has been chosen mounted behind a generic intake, given the lack of relevant experimental results. The engine has a four stage axial flow compressor driven by a single stage axial flow turbine, followed by a converging nozzle. 3-D total pressure profiles were imposed at the intake inlet and several comparative graphs of engine’s performance parameters between “clean” and distorted inlet flow conditions are given. The paper is concluded with a discussion on software’s abilities and weaknesses as well as on its potential future expansion.