PBR work on alternative skins to the largest fuel tanks so far, the 3m by 6m liquid fuel tank; alongside a few new engine variants.
Moar boosters! A smaller, thrustier engine for pushing bigger payloads into orbit. Inspired by the LR-87, it can be mounted on both a 1m frame, 2m frame, or clustered on a 3 meter engine mounting plate in pairs or quads. The first engine now shares a common turbopump exhaust with it, with its vernier engines as an optional toggle. Speaking of which - to make things more streamlined, I've approached stage decouplers closer to what happens in the real world. Interstage fairings snap onto the base of a tank (or a engine mounting plate) and you adjust them based on how big your engines are. Attach your engines in whatever arrangement you want, then attach your next stage to the base of the interstage fairing. The forces of the rocket are directed past the engine - not through it - allowing you to build in more creative ways (and stuff other things in there, like retro rockets, batteries, or other spacecraft).

Moar boosters! A smaller, thrustier engine for pushing bigger payloads into orbit. Inspired by the LR-87, it can be mounted on both a 1m frame, 2m frame, or clustered on a 3 meter engine mounting plate in pairs or quads. The first engine now shares a common turbopump exhaust with it, with its vernier engines as an optional toggle. Speaking of which - to make things more streamlined, I've approached stage decouplers closer to what happens in the real world. Interstage fairings snap onto the base of a tank (or a engine mounting plate) and you adjust them based on how big your engines are. Attach your engines in whatever arrangement you want, then attach your next stage to the base of the interstage fairing. The forces of the rocket are directed past the engine - not through it - allowing you to build in more creative ways (and stuff other things in there, like retro rockets, batteries, or other spacecraft).
