My car came with an Unorthodox Crank pulley which is smaller in diameter vs stock. After owning the car for a couple months I searched across a bunch of rather old threads involving people arguing between stock vs aftermarket without harmonic dampers or whatever.

Anyway my car is knocking at really really random times.

1. Sometimes at low RPM <3K RPM - 25% throttle
2. Sometimes in 5th Gear as I get on or off the throttle passing a car
3. Sometimes at other completely random times that aren't anywhere near WOT

None of this caused by down pipe rattle (tried 3 different down pipes) not transmission related, nothing else basically.

A lot of people have told me to ditch the crank pulley and I will be doing that within a week to see what the results are. Hopefully this can provide some evidence as to whether or not they are good or bad.

 

Is this your VIII or your IX? In my IX I had random knock pretty much at the same time you do, but it was related to my cams and mivec table.