  Sources of Flavor Changed Neutral Currents (FCNC) naturally emerge from a
well motivated framework called 3-3-1 with right-handed neutrinos model,
$331_{RHN}$ for short, mediated by an extra neutral gauge boson $Z^{\prime}$.
Following previous works we calculate these sources and in addition we derive
new ones coming from CP-even and -odd neutral scalars which appear due to their
non-diagonal interactions with the physical standard quarks. Furthermore we
show that bounds related to the neutral mesons systems $K_L-K_S$ and $D_1^0 -
D_2^0$ may be significantly strengthened in the presence of these new
interactions allowing us to infer stronger constraints on the parameter space
of the model.
