I still stand by the dyno testing I did with my engine :

1. always open

versus

2. keeping them closed until 4500rpm, then slowly opening them using the restrictor as the factory intended.

They should snap shut under vaccuum and under 4400rpm to clearly improve on/off throttle response.

I think I'm the only person outside of Nissan to do such testing. I too was of the 'more flow is better crowd' until I tested it.

Another pretty easy test for someone with a standard CA18 + standard ECU to test. Just stick a small g-clamp on the vaccuum hose going to the power valve. Do a couple of timed runs from a standing start, and report the difference with and without the hose clamped.