Thats what I am saying. VTEC most likely is engaging but is not able to breath at that RPM level causing a flatline in whp and torque. If you have sufficient oil pressure and the solenoid is getting voltage then vtec is engaging.
You have an AEM EMS but did you change to a larger MAP sensor. You should have the GM 3.5 bar on your setup. The stock will not support more then 10.1 psi