Proportions + Devnull + special ingredients = Derek's Mod Gold

[Suicide Junkie]

1) Commercial Grade Contra - Terrene Enigines I generate 2 movement points, but II and III generate 3. The Military grade all generate 3. This makes the Commercial a better choice for this limited point in the tech tree.

I reccommend making the Military grade engines slightly smaller, rather than increasing thrust.

That will give you finer control over the value difference between the engine types.