And people need to take that statement to heart. What a lot of people dont realize is that when they lean up their mix with an AFC, they are actually advancing the timing too. This is because the ECU uses the MAS information to determine the ignition timing. If you jack the MAS around to get your A/F right, you are also indirectly changing the timing. For safety's sake you dont want to allow the user to make a 70% correction as it would certainly be catastrophic.