by over filling the sump you are effectively taking up some of the space that is normally there for the crank case gases. by doing this you are increasing the pressure of the crank case which will force oil out your breathers, through your pcv valve and into the inlet. then onto the compression side of the cylinder which will burn it and put it out the exhaust causing excessive smoke.
can also cause over lubrication of the cylinders wich means the oil rings cant get all the oil out of the cylinder bores so some is left behind thus when combustion happends it burns the oil as well and sends it through the exhaust also causing excessive smoke.
so in short, drain some out. a 4efte and 5e only take 3.75L or engine oil.
might be a good excuse to do an oil and filter change as your already going to be under the car.
cheers
ryan