I am installing a Vermont Castings Encore non-cat and using Duravent's DVL oval to round adapter. The screw slits in the adapter are cut so that the seam is in front. This is my first install, but it seems like the seem should be in back? Am I right about this? Does this mean that I have to have the seam facing out all the way up given where the screw holes are cut in the pipe going up (I using the telescoping DVL to the ceiling box). Would there be any issues with drilling my own hole on the other side of the adapter and flipping it so the seam is in back?