create an XComArmorUpgrades.ini in the config folder
copy paste this into the XComArmorUpgrades.ini

[WOTC_TRMoreUpgrades.X2Item_TRMoreUpgrades]
;Requiem Armory
+arrVestsToConvert = (VestTemplateName = "RequiemStainlessVest")

the vest should now be converted into a vest module
the reason for why adding this here is because copy pasting that into the armour upgrade mod doesn't work, it needs to be in this mod's config folder for it to work, i already tested it, the same goes to spectrum enemies mod, lwotc enemy pack, custodian's hyperdrive vest, and alpha's drone and robotics shield vest, so you can apply the same method to the mod i just mentioned