Does the Twin Ion Engine MK2 modification make S-Loop maneuvers green as they are a banking maneuver?

Itnis not a bank. It is a Segnor's Loop. They use the same template, but in rules terms they are not the same bearing.

No. A maneuver that uses the bank template but reverses the facing of the model in the force awakens rule book is classified as a "Sengor's Loop", while a maneuver that uses the bank template but does not change the facing of the model is classified as a "banking maneuver".

That would make a 1 point card very very very good, some might even say OP.

Figured as much, it was a fun thought though.