Plausible, would say the "Myth Busters". I have seen configurational xml for nuvi 13xx for suzuki (one of the many firmware secrets) with which it seems...many things can be additionaly configured. (not very sure how can this be achived though. Experts better to say.) May idea is that maybe you should thing in that direction rather than playing with the FW. BTW from where can the dnx520vbt FW be downloaded?