THE ISSUE:
I have heard this is multiple tunes, including the Perrin, Vish, and Visconti.
Vish explained it's simply a large change in VVT timing in a small amount of RPMs. (5 to 40 degrees)
I'd like more technical information on what exactly is creating the noise. Perrin said its resonance, Vish said its "rasp." Sounds like shit, and like valvetrain noise to me. With all of the tuning drama recently...
I'd like a straight answer as to
mechanically what is happening, because if the long term effects of reducing torque dip has mechanical implications I want the VVT timing cut back.
SOUNDS OF THE MODIFIED VVT TUNING TO REDUCE TORQUE DIP
Here are the logs to accompany the video:
New comparison video, stock VVT map vs aggressive VVT tune:
Noise can be heard here Perrin Tune: at time -31.00 and -23.00
http://www.freesound.org/people/dezoris/sounds/191194/
And here on Vish dyno: At 22 Seconds
At 22 Seconds
UPDATE: 3/11
Perrin modified my flash file to go back to a stockish VVT map from 2800-4200RPM range. After the flash the valve train noise is now gone.
The argument remains, tuners say the noise introduced from the optimal/aggressive VVT tuning is normal. Tuning VVT agressively can be done on FI or NA the same way, depends on the motor on how much noise it generates.
Given the unproven long term mechanical implications of those statements (if any) going back to a conservative VVT setting is good insurance for now.