  We examine the spectrum and boundary energy in boundary sine-Gordon theory,
based on our recent results on the complete spectrum predicted by closing the
boundary bootstrap. We check the spectrum and the reflection factors against
truncated conformal space, together with a (still unpublished) prediction by
Al.B. Zamolodchikov for the boundary energy and the relation between the
parameters of the scattering amplitudes and of the perturbed CFT Hamiltonian.
In addition, we give a derivation of Zamolodchikov's formulae. We find an
entirely consistent picture and strong evidence for the validity of the
conjectured spectrum and scattering amplitudes, which together give a complete
description of the boundary sine-Gordon theory on mass shell.
