TD torch cut height enquiry

Hi,

I have a little Thermal Dynamics Cutmaster 38 with a 30amp drag tip. I use a floating head without THC set to zero of each cut.

I'm trying to find out the correct distance to pierce and cut with using this TD machine. What i'm reading suggests I should be cutting at about 3mm above material but since the plasma has a 30amp drag tip it works best on thin steel at 0. However 0 is not realistic. I'm just thinking about the consumables and cut quality and whether there is a standard height I should be looking at.

In Sheetcam I have the settings for 3mm mild plate set to:

kerf 1mm
Feedrate 1500mm/min
pierce delay 0
pierce height 9mm
plunge rate 300mm/min
cut height 2mm

Thanks