Elon tweeted that future versions will be 10% to 20% longer. If the 20% longer development happens then the stacked rocket will be 144 meters long. Adding 24 meters would be over 60% of the length of the Space Shuttle orbiter which was 37 meters long.
The SpaceX Starship upper stage is 50 meters long. If this is made 20% longer then it would be 60 meters long. The Space Shuttle on the launch pad with its external fuel tank and side boosters was 56 meters tall (184 feet).
If the Starship payload area could be stretched by ten meters then the payload volume would increase from 1000 cubic meters to 1800 cubic meters. If fuel in Starship increased then the stretched payload volume might only increase to 1400 cubic meters.
Walter Isaacson's Elon Musk biography talked about the SpaceX 1337 having critical breakthoughs beyond the SpaceX Raptor.
Elon Musk and SpaceX looked at extreme ideas like deleting the whole hot fuel gas manifold and merging the fuel pump with the main chamber injector. Elon Musk told his team that We are on a deletion rampage". All questionable tubes, sensors and manifolds were deleted. Elon also has looked at removing the entire skirt of the booster.
The performance of the SpaceX Raptor engines is already very good but LEET 1337 will have even higher chamber pressure which will enable more thrust. The SpaceX LEET 1337 engines will be simpler, lighter and cheaper. SpaceX will likely be able to build them at ten times the production volume from the same sized factory that will now make 4000 Raptor engines each year.
Starship is the biggest rocket ever built ???? pic.twitter.com/SdCxp156GE— Tesla Owners Silicon Valley (@teslaownersSV) September 9, 2023