Tony,
I wouldn't trust stock knock control as far as I can throw it. Throw any decent knock detection gear on a stocker and belt it. You'll be surprised.
Point to note with these motors. They will keep making torque well past the knock threshold.
Where are you located mate?
It's quite possible if the bushes have been installed at the incorrect depth the front supports for the diff will contact the cradle under load and transmit noise and vibration.
Just remember the tuning interface is only part of the deal. You also need equipment to measure afrs and monitor knock.
The gear will soon pay for itself if you continue mods and don't have to pay for retunes.
Plus the day you stop learning you die. So keep learning.