Hello
Thank you very much for your comments.
Perhaps it is a problem of the airflow, Beltempo wrote. I have a meshgrill behind the grill and perhaps this reduces the airflow. But I think the meshgrill is important to prevent stone hits which can damage the radiator. I also have the Brooklands front splitter which also reduce the flow.
I drive a lot in the alpes were you drive with low speed and hard work for the engine. Therefore I think it will make sense to replace the radiator to a bigger one.
