That's an area I should highlight on my engine picture. Since the boxer engine is a little different configuration than most 4, 6, or 8 cylinder motors it is hard to show everything. Either end of the spark plug wires are good areas to avoid as well. They should be good and sealed, but you can get water down the valve cover pretty easily on some cars and you can cause damage to the cap and rotor if you are dealing with an older car that probably needs a tune up anyway.