I have a 318I and in the pressure workshop they tell me that my head lends to change or add an angle of the valve to the valve and that will give more potensia to the car and this this work is done to the racing cars but I do not know how sure this modification will be made and you
A lot of power, and a lot of expense and fuel that work is known as crusing the cam, or change of angle of valves, the release will never be stable but made as a demon.