I have put larger but more flexible rubber bobbins on the mounts of my G56 pipes plus a load spreading plate on the front mounting on the inside of the body. That reduced the clattering considerably. The other thing I did was to lubricate the clamps and their locking screws from the down pipes to the silencer systems with Permatex ultra high temperature anti-seize, got them really hot and tightened them hot (my burns should heal soon). https://www.amazon.co.uk/Permatex-81343-Anti-Seize-Lubricant-Tube/dp/B0002UEOLO Again that reduced the clattering.
