I have heard that people are having trouble when they fit the 69mm throttle on Ecotec. Saying the mixture is too lean and gears change lower and it needs a tune with it. The memcal that comes with the kit, does that stop any of that?

The main reason that people can have issues when installing larger throttle bodies on an ecotecs, is the fact that the throttle response is quicker then what the factory calibration/tune has taken into account. If has nothing to do with mixtures. If specifically requested, we can definitely supply a calibration/tune that is compatible with our larger throttle bodies.