Actually, as long as you don't touch anything that affects MP (or War Assets/Galactic Readiness) there is no problem. I added 3 full set of armors + unused pieces and I don't have any problem.
that not what the compagny representative said when we ask them the question about it, EA will do no discrimination if it affect the single player or the multiplayer
How did you modify the helmet color?
I already know how to change the helmet of a full armor, but this is new for me.
I added 3 full set of armors + unused pieces and I don't have any problem.