VTEC was designed for high rpm power. The main reason for VAFC are to tune chipped ecu's and modded compression and heads. Most chipped ecu's push the VTEC cross-over forward and change the fuel map. To see true gains from a chipped ecu you need some sort of controller to properly tune. VTEC controllers are also used with aftermarket cams. At lowered cross-overs on the dyno there is a drop in hp at the cross-over point. You want a consistant gain in hp to the peak not a drop at x-over.