The availability of a high momentum transfer (0.3<Q(A-1)<5.5) with an energy resolution of few μeV, makes the spectrometer IN13 particularly suited to the study of the local dynamics of soft matter, such as polymers and biological systems. In the present configuration the performance of the instrument is overall limited by the low incident flux. A progressive upgrade of the instrument is planned in order to improve this and also to increase the instrument versatility. In this way, different possibilities other than the standard configuration, will be available in order to allow for the best compromise to be defined between flux, energy resolution and Q-range for each experiment. The first step of this project consists of simulating the instrument and the different modifications envisaged. The results of our Monte Carlo simulations of the primary spectrometer together with data from experimental tests show that IN13 could be modified in order to obtain a gain in neutron flux up to a factor of five.