  We consider a model of the early universe which consists of two scalar
fields: the inflaton, and a second field which drives the stabilisation of the
Planck mass (or gravitational constant). We show that the non-minimal coupling
of this second field to the Ricci scalar sources a non-adiabatic pressure
perturbation. By performing a fully numerical calculation we find, in turn,
that this boosts the amplitude of the primordial power spectrum after
inflation.
