Engine upgrade does give the defender another unique ability: boost after k-turn
Tycho and Biggs make that ability not-so-unique.
However it would be certainly useful allowing the defender to boost before revealing its maneuver (sort of a pseudo-advanced sensors). A title could give the defender the boost ability, and the additional ability to perform it before revealing its maneuver, if he wishes. That would fix many of its speed and maneuvering issues while still flying different to other ships.
Edited by Jehan Menasis