I started with Cristian's posted mod setup today and did 2 things. I took off the swaybars, and went 16.5 front/13.5 rear. My 17.5 car had 5-6 seconds on 2nd place and had the other 5 lapped in today's main.... Also had fast lap I think. Traction was medium and the layout was pretty fast.
Oh, I had a front gear diff with 500k also. Throughout the day I played with 1mm shims on the link, but at the main they were just barely angled.
VERY pleased with it