  We study the evolution of the equation of state of a strongly interacting
quark system as a function of the diquark interaction strength. We show that
for the system to avoid collapsing into a pressureless Boson gas at
sufficiently strong diquark coupling strength, the diquark-diquark repulsion
has to be self-consistently taken into account. In particular, we find that the
tendency at zero temperature of the strongly interacting diquark gas to
condense into the system ground state is compensated by the repulsion between
diquarks if the diquark-diquark coupling constant is higher than a critical
value $\lambda_C=7.65$. Considering such diquark-diquark repulsion, a positive
pressure with no significant variation along the whole strongly interacting
region is obtained. A consequence of the diquark-diquark repulsion is that the
system maintains its BCS character in the whole strongly interacting region.
