I dont see an option for it.

Personally, I'm letting them 'Improve' Armor as if it was wargear, but only by piece.

Ah I could not find rules for this eather… I dont think you can, I guess you can just by it like any other item and drop the flak vest?

I'd say you should be able to upgrade it using the Upgrade Wargear option, as right now, it's pretty much useless because most of the items under Wargear don't benefit from improved quality (more than 75% don't even have the option, and a few that do aren't even available in the standard kit unless purchased separately).

The option to improve the quality of other gear should have been included, although I believe the original intent was to allow improvements to all pieces of gear (taking the Vostroyans as an example, they have both a good quality lasgun and a good quality carapace chestplate).

This is done through their Regimental Doctrine and/or acquisition points for the final customization of the regiment's standard kit (table 2-6; p34). Also, once you have spent points to acquire a piece of wargear off of the table it then becomes "standard" for the regiment and can be improved per the top two options.

-=Brother Praetus=-