I wanted to mention this because I found it quite interesting. I was doing an update on some modules in an '09 Suburban with a 6.0 that belongs to a government agency and browsing around the various options I found a calibration for the ECM described as "use only for low power complaints, audible spark knock may occur at times" ??? I was so curious I almost flashed it to see it (that may be an option on another vehicle in the future). So I was just wondering, GM is actually willing to advance (I assume) the timing to improve customer satisfaction with acceleration on the big trucks to the point that it knocks loud? Doesn't that damage the engine? Or maybe they are hoping that only occurs on severe applications? Either way I found it interesting.