I've tried to make those strips taper with the Normal Map without success.
What I would do is remove about a third of the line from each end, use the rectangular selection tool to select an area equal to the original line, then do a 2-3 pixel gaussian blur.
Are you guys talking about the airflow fences on the outer portion of the wing? if so, those are supposed to be raised, however the base is wider than the fence itself; you wouldn't want the whole thing raised as a bump on the skin.
Very fake looking to me. Find a picture of a real 190 that has a wear pattern that you like and try to mimic it.