  We consider the production of gravitational KK modes via cosmological
photon-photon and electron-positron annihilation in models with large
factorisable extra dimensions. We place constraints on this production using
recent results from a joint analysis of the power spectra of the 2dF Galaxy
Redshift Survey (2dFGS) and the cosmic microwave background (CMB) anisotropies.
We obtain a more accurate upper limit for the temperature corresponding to
matter-radiation equality and show that, even for the case of 6 extra
dimensions and a fundamental scale of 1 TeV, a period of inflation is required
that ends at a temperature much lower than that of the QCD phase transition.
