I'm guessing you have a turbosmooth applied, or perhaps an opensubdiv modifier. I don't know what the accurate shape of the aircraft is, but I presume you do. The best way to make the seam the same on both sides of the seam, is to use the same geometry on both sides of the seam. If the part in the front transitions to round as you've modeled it, by starting (with non-subdivided topology) that part with a clone of the polygons from the other side of the seam, you'll know the seam will look right. Transitioning the polys between the round part of the front and the squared off row of cloned polygons can be done many ways, including ffd, as Fadhil has taught.
