I know a couple people who have swapped from Cossie management to Megasquirt or Omex and the chatter quietens down. Also others that went from EFi to Cossie and the chatter got really intense.

I can't understand why it makes a difference and i don't know what other variables they changed. I would think the "Chatter" is governed by mechanical parts, so the turbo and its pipework etc. So it shouldn't make a difference but somehow it kind of does.