I run mine a lot higher than that for PET. When you're printing, the filament being pushed into the nozzle will create a high pressure zone behind the nozzle. When you stop pressing the filament through, the pressure in there will still ooze filament out. So you need to relieve that pressure by creating a vacuum. The best way to do that is suck that filament back out of there quickly.
A little coast at the end of the path will help as well. It will not only bleed off any filament still trying to extrude, but it will also wipe the tip. This will all help to eliminate stringing.
Best thing to do is find a small test print that will have small towers. You want something that will cause the printer to print one spot, then jump to another spot quickly. Play with your retraction distance and coast settings until you get a clean print. Just watch you aren't leaving little tiny gaps everywhere due to too much retraction, or too long a coast setting. I typically run around 5mm retraction and .2mm to .5mm coast with PET if I remember correctly. But it's been awhile since I printed PET.