I had quite a bit of knock retard in both Stage 1 and Stage 2, likely owing to the gas quality here in SoCal, along with our hot weather (90+ degrees). Though it was never on hard acceleration, so I was told it wasn't a big deal. Finally got my IC upgraded and now it doesn't retard so much anymore (only typically when I let off the gas from a pull, or half throttle overtake from low RPM; never any on WOT) and my car's got a lot more pull. Really makes a difference if you're seeing hot temps, though I don't know how hot it is in Canada right now.