At around 2000 RPM, if you "get into it" to try to accelerate without downshifting. It's an '05, with the 1NZ-FE and 5 speed, I tried premium gas to rule out pinging/carbon buildup, and even swapped out the M1 0W30 AFE for 5W30 EP to see if maybe it was engine related, made no difference. Any Scion or Yaris owners ever hear this? Hoping it's not a cam phaser problem, it actually makes a growling noise when it does it, 44K miles on it.