Hi Gary,
Sorry was just browsing the thread today and saw this, and sorry to interrupt Tony, but I had another thought, (all else being equal) if the car has got too much turn in / steering or the car gets twitchy/loose in the rear under breaking you might want to run less droop in the rear, I.E. short ball cups instead of long, (basically a shorter rear shock) this can help with both stability and traction rolling as it allows less of the weight to transfer to the front wheels under breaking, as it sort uses the rear wheels/tires as ballast to keep the rear end a little more planted. I know it often sounds counter intuitive, people often think that for more rear grip you need more suspension travel, and to a degree that's certainly true, but usually some of the other effects of more rear droop, can be a looser rear end under breaking / turn in, the car wanting to "trip"/twitch more over smaller bumps/ruts (in certain situations), and being more prone to traction roll.
Obviously, as tony and you were discussing, tires are usually 80% of getting are car working for a specific track so I would start there, is the upcoming event at the same track? In other, words do they usually run hole shots on the track your on now? Also, compound is prob. at least as, or even more important then tread pattern or carcass const. etc. so I.e. M2 hole shots are completely different then M4.
Hope that helps
