As 451Mopar said Alpha-N is TPS vs RPM. It is NOT the way to tune a modern EFI system unless you have no other choice. It's fine for all out race engines but you can't get drivabilty since it has no way of sensing load. Speed Density is preferred, but it can be tricky if you have low vacuum at idle. The Holley Dominator does allow Alpha-N at idle and then transitions to Speed Density. Although that is cool, I have never needed to use that feature even on all out drag race motors.