Yes I run the rears on setting 4.
5 is the stiffest.
I also have the 2000 bullet springs.
On the front side I have the tokico drag struts set on 4 also.
The first launch on setting 1 pulled the front tires way up. LOL
Everything seems to work well. I am going to play with tire pressure and launch RPMs as I feel the car should be able to 60 in the 1.3x range.
Based on my videos the front tires seem to stay on the ground with full strut extension to the shift point.
What is your current spring / shock setup?