  We give necessary and sufficient conditions for nuclearity of
Cuntz-Nica-Pimsner algebras for a variety of quasi-lattice ordered groups.
First we deal with the free abelian lattice case. We use this as a stepping
stone to tackle product systems over quasi-lattices that are controlled by the
free abelian lattice and satisfy a minimality property. Our setting
accommodates examples like the Baumslag-Solitar lattice for $n=m>0$ and the
right-angled Artin groups. More generally the class of quasi-lattices for which
our results apply is closed under taking semi-direct and graph products.
  In the process we accomplish more. Our arguments tackle Nica-Pimsner algebras
that admit a faithful conditional expectation on a small fixed point algebra
and a faithful copy of the co-efficient algebra. This is the case for
CNP-relative quotients in-between the Toeplitz-Nica-Pimsner algebra and the
Cuntz-Nica-Pimsner algebra. We complete this study with the relevant results on
exactness.
