  We analyse the gravitational wave and low energy signatures of a Pati-Salam
phase transition. For a Pati-Salam scale of $M_{PS} \sim 10^5$ GeV, we find a
stochastic power spectrum within reach of the next generation of ground-based
interferometer experiments such as the Einstein Telescope, in parts of the
parameter space. We study the lifetime of the proton in this model, as well as
complementarity with low energy constraints including electroweak precision
data, neutrino mass measurements, lepton flavour violation, and collider
constraints.
