Does the Shozoku of the Night Wind add to AC, even if you are already wearing armor? I initially didn't think it did, but when I was tooling around in Hero Lab it said that the Ninja Pajamas of after dark gas added to AC, even while wearing a suit of armor.
Hero Lab is in error. It is a "+2 armor bonus," not a "+2 bonus to armor class." So no stacking. Can't think of any way to interpret that differently, really.