[Apricot Slice]

I want to help if I can but am too lazy to read the whole thread so excuse me if I am repeating things.

I would make sure there is no sloppiness in the grommet department.
If the grommets squidge about under cornering load it will cause additional steering and nackker your driving. (chassis flex will do the same thing because of the big distance between servo mounts and suspension mounts.)

I am running kit (sstox) tires, green springs on front and mardave pod at rear with no diff. (sstox rear is silly) It feels pretty good. My test driver has a diff in his and raced twice and got first and a second.