I have done this many times, the main thing to remember is that too much RTV will restrict the exhaust flow.... That is to say, how ever much that squeezed out and you had to wipe from the out side, is now dried on the inside. A very light bead will do. Apply the bead, tighten just enough to squeeze a little out (Don't wrench it down) and then let it cure. Once it is cured (over night) you can take out the screws one at a time to add thread lock and tighten the flange down evenly on the RTV gasket. This will give you a long time seal and no possibility of restriction to the exhaust flow.