Multiple Application Curvature Adaptive Optics (MACAO) systems are used at the coude focus of the unit telescopes (UTs) at the La-Silla Paranal Observatory, Paranal, to correct for the wave-front aberrations induced by the atmosphere. These systems are in operation since 2005 and are designed to provide beams with 10 mas residual rms tip-tilt error to the VLTI laboratory. We have initiated several technical studies such as measuring the Strehl ratio of the images recorded at the guiding camera of the VLTI, establishing the optimum setup of the MACAO to get collimated and focused beam down to the VLTI laboratory and to the instruments, and ascertaining the data generated by the real time computer, all aimed at characterizing and improving the overall performance of these systems. In this paper we report the current status of these studies.