Sounds intriguing—let’s crack the numbers. First, what’s your switching frequency and the component specs? I’ll map out the conduction paths and estimate the I²R losses. Also, tell me how you’re handling the ESR of the output capacitor and the inductor’s core losses; those usually bite at high efficiencies. Once we have the equations, we can run a simulation to see if the theoretical 99 % holds up when you load it.