I am not sure what properly tightened is for these headers. At first it felt too loose, so we tightened it down until it was really tight, and then it kept leaking.
Eddie, those aren't washers, those are the springs that came with the stock hardware.
You should scrap them and buy Speed Daddy's. best bang for your buck header and don't leak.
take the donut gasket out. coat the edges that seal it in a layer of RTV and let it dry. reinstall donut gasket.
they'll seal. i did this with the TOGs that i owned.