You can change the rpm VTEC engages out with a $20 rpm activated swtich. All it basically is controled by is one wire from the ECU to the VTEC solenoid. The problem is why would you want to. Honda designed their head/cam setup specifically for the stock changeover point. If there was more power to be gained by moving it, it would be there in the first place. Also, when VTEC engages, the engine is fed more air, so it needs more fuel. If you change the VTEC point alone, the extra fuel in the ECU's stock map won't come on until it should. You could run lean if you move it down and rich if you move it up. It's not really dangerous, just no ideal.

An piggyback fuel computer like a V-AFC (that also can change the VTEC point) is useful for small adjustments to the fuel mixture to produce more power, assuming you have a dyno to tune with. The ability to change the VTEC point would also be useful if you ever changed cams to one that perfer a different changeover point. The fuel tuning abilities will also help fill in the fuel map as well. Seeya.