This document examines the effect of pilot flame instabilities on pressure in assisted combustion systems. It analyzes combustion in the annular chamber of an Ansaldo-Siemens V64.3A gas turbine. Numerical simulations were performed to characterize mixing and temperature distributions at the outlet of the turbine's premixing vortex. The results show non-uniform mixing and worsening distribution with increasing load. Modifications to the injection geometry and flow parameters may help optimize the reaction process and stabilize combustion over a wide load range.