Just what Dizuster said.
I just started index racing in footbrake only classes. I'm racing with a lot of guys that have it down to a science (mostly by adding weights) and they are real good at it. I started by trying to adjust my shift points and actually did fairly well but not good enough against the hardcore index guys. At my last race the car ran two identical numbers during test & tune but it was running too slow. Then I realized I had been working on the top of my motor and when I reassembled it I forgot to adjust the throttle linkage. I adjusted the linkage correctly but after the race was over it hit me, adjust the throttle linkage to the index.