Here is a calibration run I made plus one someone else made. The first image shows that lowering temperature eliminates stringing. I used 4.5mm retraction. I printed slowly only because the part was so small and hollow that I needed time to adjust the temp and mark the lines with a sharpie and take notes all at the same time. I wasn't able to go down to 170C because when I tried, Cura turned off the extruder (that part not shown) and ruined the test. The next image was created by someone else