I have noticed that none of the Ion drives that I have seen so far such as the stock "Dawn" or any of the ones from mods like Near Future Propulsion have neutralizers on them. In real life these are essential to the functionality as they ensure that the exhaust gases don't re-enter the engine, canceling out the thrust provided.
Modeling-wise it would be easy to implement - just stick a tube on top of the engine that also glows as the engine fires. See pictures
This is a very small point but still I think it would add to the realism, which I believe to very much a core value of this game
