I do have the NVH fitted as I had to have a new chassis fitted after accident.
I have wondered if this is a factor.
My knock or clunk is only apparent ,post changing down on overrun in to second or first and letting clutch out with low rpm on the engine. It doesnt matter how gentle I am with the clutch. it doesnt appear on acceleration so its more like front lash than backlash( im joking but you get the idea)
+1 on the NVH bracket playing a part in the knocking sounds. I reckon that it may be bouncing up and down under certain circumstances and hitting the chassis (or something else).