Quoted by Monkeywrench:
Using the PFC, we fully tuned the 2ZZ in using ONLY the small cam, then ONLY the large. Then we overlaid the graphs. Drum roll please... the crossover occurred at about 6300 RPM. We got our best results during tuning the switchover by changing over at 6000 or slightly after because of the time the VVTi actuator takes to react.
See results at:http://monkeywrenchracing.com/mwr_celica_gts.html
Why did we do this? To get people to FINALLY stop requesting a way to change over to the large cam earlier. You'll lose power, and here is the proof. We successfully did change the VVL point with the stock ECU over a year ago, the results were poor though. The reason is that the big cam dosen't offer an advantage until after 6000 RPM. Plus, if you're using the stock ECU, you can't get tune the VVL to work with the earlier VVT.
With the addition of a turbo this changes. More on that later
Note: Honda switches to the large cam profile later than optimal for whatever reason, which is why VTEC controllers help those engines. Toyota did not make the same choice in their tuning.