PETG 230C Nozzle and Bed 70-80C, retraction I use from .8 -1.1 mm 30mms for retraction speed, print speed depends on part size and shape but 30mms is a good start. Z offset needs to be correct for your layer height. Use highest layer you can for your nozzle size. Extrusion Multiplier must be correct and PETG must be dry for good results. As I said in my first response, if you are under extruding and you have used PLA first and did not clean the nozzle with cleaning filament or other more difficult mechanical means, you are probably restricted.