I don't know what planet you're from, but it's common knowledge that KA VTEC syndrome is a bad knock sensor. The ignition map disregards knock sensor feedback after 4800rpms. So your falsely high reading dead knock sensor is pulling timing all over the place until 4800 and then it goes back to normal. This is probably also putting a dent in your fuel economy as well.

I have no idea what's up with xnissanx's car....