In order to further the understanding of boundary layer ingestion (BLI) engine integration concepts the DLR project AGATA³S aimed at modelling and evaluating the inhomogeneous inflow into turbofans positioned on either side of the rear fuselage. Besides investigating increased flow-induced blade vibrations as well as the excitation of additional noise sources, a focus within AGATA³S was the assessment of BLI on overall aircraft performance. The present paper discusses the results of a parameter study carried out on the DLR TuLam aircraft in which a UHBR engine was embedded into the rear fuselage to varying degrees in order to understand the relationship between degree of embedding and total aircraft thrust requirement. The TuLam underwing-mounted engine configuration was used as a reference. The performance data as well as the phenomenological effects of BLI engine integration are assessed.