I started this last week, finished it today. Not going to give a lot of details of the measurement, but we drive the ISI hard at low frequency in one direction and adjust some cps align elements until a hooked line becomes mostly straight. This will give us some gains in the low frequency region. St2 still needs to be done, but should go relatively quickly. Also need to add sensor correction, which I'm starting to look at right now. Posting a screen of the St1 cpsalign values here for posterity.