No one turbo gets 100% of the exhaust. The other turbo is blocked off at the turbine outlet end, and the inlet is blocked.
Then both turbos are running and the inlet valve is opened.
The old mazda rx7 had this sort of system.
The primary turbos is the ihi rb5, max power 150 - 180. That is less than what the engine provide n/a so this turbo will stop at 3000 rpm.
Should boost from idle though - Lag whats that then?