I haven't read this thread, but I wanted to share a quick data point about the Civic Si that I just bought yesterday (new). I did some datalogging with a FlashPro, and was blown away by the amount of knock retard that the ECU is applying across the whole rev range. It's around 10 degrees retard for most of the range, which results in a about 15 degrees advance until it gets to 6K, then it climbs a few degrees as knock retard tapers a bit. It also runs uber-rich, maxing out the AF sensor at 10 above 5500. Torque drops off HUGE as well, which causes HP to go flat from 5500 to redline. I've only put about 150 miles on it so far, so I guess it's possible that Honda implemented some sort of "mileage compensation" in the tune that makes it perform poorly during break-in, but I really doubt that. I think it's much more likely that the dealership just put low octane fuel in it. I will definitely put high quality high octane fuel in it when I run this fuel out, and will see how that changes things.