I suspect it's there with the air box and plumbing, but muffled because of the intake tract. Removing all the junk allows the melodiuos crickets to roar. I get it under hard acceleration, but just winding up the throttle doesn't usually deliver the racket. You reduced (did not eliminate) part of the issue. I used Tuneboy to open the secondaries to 100% so I don't have a whistle, just the crickets. if you get it completely sorted and locate the culprit, post it up.