How specific should I be in my SOP, regarding courses and thesis subject? I know there isn't an absolute answer but I certainly could use some hindsight.
I'm writing an SOP for an Msc at TU Delft in Aerospace, and I am having trouble with two parts of it : specifically I'm required to provide hypothetical thesis topics and explain why among the different tracks in Aerospace I want one in particular. 

First of all, regarding the track, I've explain my interest by explaining in detail which courses I'm really eager to follow and which part of these courses I feel are the most appealing, but I'm not sure if I should be this is the right approach, I'm also wondering if I' not going too much in details by being so specific about the courses.

Then about the thesis subject, I know what the focus of the Msc is going to be , what courses I will follow and what the research themes are but I don't know what thesis subject are going to look like, and what is a relevant subject or not. So I don't know if I should stay a bit generic and talk about the fields of research or try to make a concrete thesis subject anyway ?

Thanks in advance.
The expected Statement of Purpose probably differs between fields, countries and even institutions. In economics, it is not a major factor in admissions even if required. People write about their general interest area and proposed topic, with the expectation that their actual thesis may be completely different. 

As I understand it, the purpose of the SOP is just to demonstrate having an idea about the field in general and being able to distinguish subfields. As mentioned, this may vary across fields.