On C*-completions of discrete quantum group rings

We discuss just infiniteness of C*-algebras associated to discrete quantum groups and relate it to the C*-uniqueness of the quantum groups in question, i.e. to the uniqueness of a C*-completion of the underlying Hopf -algebra. It is shown that duals of q-deformations of simply connected semisimple compact Lie groups are never C-unique. On the other hand we present an example of a discrete quantum group which is not locally finite and yet is C*-unique.