Nice one !
If you are only running a single box RC40, I'd suggest fitting a second box to remove that drone. It'll be to do with cam profile and the position of the box you have, which you can't do much about.
Too much toe out on the front or too little toe in on the rear will make it twitchy and want to keep turning in. I note your rear figures have a zero toe angle on the rear, and as Oz suggests, adding shims in the rear reduces Toe.












