Last week we hot-fired an 80 kN LOX–LCH4 staged-combustion unit and a 2-point bump in turbopump polytropic efficiency bought about 7 s of sea-level Isp — real margin, not spreadsheet noise. In your programs, have altitude-compensating nozzles, active tip-clearance control, or smarter FADEC schedules moved the needle more than cycle tweaks, and by how much?