On carpet, I have had the best success with Sorex 24 in the front and Sorex 20 in the rear. At a large event where a lot of rubber has been laid down, I might go to 24/24 or even 28/24, and on a really lose surface I've tried 20/20.
Nobody we race with uses tire warmers (that I know of) but they may help. Normally we just do a couple "hot laps" before a heat and then just take it easy for a lap or two until the traction comes up.
We've been using TQ or TQ Mod traction compounds. Paragon works as well, although it has been banned at some indoor tracks due to the wintergreen odor. Traction compound isn't a necessity, but it helps to keep your first few laps in order.
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