Every tuned Subaru owner should be able to pull and read a basic log — it's the difference between knowing your engine is healthy and hoping it is. Log a steady cruise plus one clean third-gear pull, with at minimum: DAM, feedback knock, fine knock learn, AF correction/learn, boost, and AF ratio.
DAM (Dynamic Advance Multiplier) is the ECU's confidence score, from 0 to 1 (or 0 to 16 on older cars). It should sit at maximum and stay there. A DAM that drops and recovers occasionally is the ECU doing its job; a DAM that drops and STAYS down means persistent knock — stop doing pulls and find the cause.
Feedback knock is the ECU reacting to knock right now; fine knock learn is it remembering where knock happened. Occasional minus-1.4 blips at low load are often false knock from accessories. Repeated retard at the same rpm and load under boost is real — that's the log you send to your tuner today, not next month.
Fuel trims (AF correction plus AF learn) show how far the ECU is correcting from the tune's targets. Within about plus-or-minus 5 percent combined is healthy; past 10 percent means something changed — a boost leak, a failing sensor, bad gas, or a tired pump. Trims are your earliest warning system; knock is your last one.
Tuning changes engine behavior. Numbers here are typical, not guaranteed — your fuel, climate, and hardware matter, and a professional calibration for your specific car always beats a generic map.