> they need to find 50 tons more capacity by shedding weight elsewhere in the system

In it's current test iteration they are overengineering many parts and opting for heavier, cheaper versions since currently the ship gets thrown away each time. One example are the grid fins. On Falcon 9 they are made of titanium, but on Starship they are steel probably because it's just easier to work with and why put in extra effort for something that will end up in the gulf? If they just swap in titanium grid fins they'll save 3 tons in the weight of the booster and even more fuel since that extra weight won't be getting carried up.