Biggest things changed are the plumbing inside the booster (much beefier, now supports starting all engines at once), and a new version of the engines, raptor v

Biggest things changed are the plumbing inside the booster (much beefier, now supports starting all engines at once), and a new version of the engines, raptor v3 (more robust, and saves about 1 ton of mass per engine). Cool image comparing the three versions of the engine. In addition to making the engine itself a bit lighter, moving all that stuff to the inside of the engine let them eliminate a whole bunch of heavy shielding in the engine bay. https://ibb.co/pr0gx688 https://ibb.co/pr0gx688