Great post Luke, couldn't have put it better myself. Although in my own car, Knock sensors have been off for ages. I believe that oscillations in the timing curve (caused by false knock/and my forgies) hurt average power at the track. There are a heap of tables that apply to knock sensors, nearly all of which I don't have the gear to correctly calibrate. I've seen quite a few tunes now, it might be something to do with a few of the tables not crossing over into HP (which I doubt) but it seems some tuners are using the knock sensors to trim the final ignition timing and could not possibly be logging the timing curve to compare against the desired maps in the tune. Apart from the whole dyno x vs dyno y variances etc I think that this is the reason some cars make good hp on the dyno but don't perform well at the track. I can't prove that though as I refuse to tune anyones car that way.