Now I know we have a problem somewhere. I just did a test launch with the simulated combined weights of a fully tanked Centaur G Prime upper stage, it's support structure and Galileo which masses 25 mT, something according to my sources would have required 109% on all three SSMEs.
Also increased the mass of the empty mass of the ET to that of a LWT. Still, no problems getting into the planned orbit for Centaur G Prime missions! And that is with the SSMEs at just 104.5%!
We're lighter and/or running something hotter than the real thing.