  We present the complete Kaluza-Klein spectrum resulting from the
compactification of IIB supergravity on S^5/Z_3. Knowledge of this spectrum
allows us to perform a holographic computation of the difference of central
charges c-a of the dual SU(N)^3 quiver gauge theory. We find the numerical
value c-a=3/16, in exact agreement with the field theory result.
