Yes, the finn says: the turbo engines are tougher, but based upon experience the non turbod 4-valves could be "safe" with 400. good enough for me

Is it confirmed that non-turbo 4-valve do not have oiljets?

Just a thought.., the 4valve head must flow a whole lot more than the 2-valve being able to produce 136 hp NA, when the 2valve-turbo need 0,9bar to produce an airflow to support 11hp more..