The engine upgrade us the best upgrade for it. Boosting after a K, or after a straight green is just what you need.

But you Can't even bring 3 Defenders with an EU which is just ridiculous!

In my experience Deltas need a focus token ready for defense.

So no action left for boost anyway.

TIE "Twin Ion Engine"

In my experience Deltas need a focus token ready for defense.

So no action left for boost anyway.

i think that a lot of times positioning or your movement options for the turn after are even more important than a token. And changing the angle of this ship is extremely important after a K or a green straight.

The only Defender pilot I would consider to equip with an Engine Upgrade is Vessery.

I had once in an tournament vanilla Yorr + Vessery with Elusiveness. They made a fairly good team.