Yesterday I spent a couple of hours on a local asphalt track and I think I nailed down a good setup for my Ultimate.
Oil: 450 cps all around
Springs: 6T Front - 6,5T Rear (from 3Racing Damper Spring Set #SAK-49)
It feels very balanced and the rear stays in place. I did some small adjustments to droop and a couple of other things, but the springs and the oil change was the most effective.