they are clear
This is due to the combination of
two effects: increase of nozzle internal thrust; and reduction
of nozzle external drag.
TVC nozzles modify the shape, true any axisimmetric nozzle changes the shape of nozzle thus they increase thrust, however the ITP nozzles modify the nozzle into a shape that non TVC nozzles can not achieve therefore it actually increases the thrust further and reduces the external drag but remember this, ITP`s nozzles uses a shape regular and conventional nozzles without TVC nozzles can not achieve.
By changing the direction of thrust it changes the thrust yield thus increasing the thrust yield of EJ-200 beyond what it yields without TVC nozzles