I had made several EDF test and I saw what is important is the clear airflow in the EDF.
I didn’t like the older exhaust pipe parameters of the CHANGESUN Ø 120mm 4 blades so at first I redesigned a new exhaust pipe where I did not change the outside diameter only I reduced the diameter aft of the electro motor air cooling canal.
After that I will make a seven degree exhaust pipe Ø 100mm at aft then I test these two exhaust pipes together.
I hope I will get better result in this test than in the old one.