Hi Bradley,
We’d love some photos of your results and screenshots of your settings. 
The dot width, aka Beam Size is fixed depending on the laser source and the lens you are using. Maybe, you are referring to the Dot Width Correction
For a 150mm lens, your Beam Size is around 0.05mm.
A DPI of 6000 equals a Line Interval of 0.0042mm. → way smaller than the size of the beam. This results in the lines overlapping and you won’t gain any quality improvements.
Set your line interval closer to the actual Beam Size. You can do an Interval Test to find a good value.
Look for the sample square where the scan lines touch without overlapping.
Further possible improvements are:
- Use air assist to blow away engraved material and cool the material.
- Use more passes with lower power
- Enable Cleanup Pass with a tighter Line Interval, higher Frequency, and lower Max Power
- Focus slightly deeper into the material so the focal point is closer to the bottom of the cut.
Keen to see your results!