I've read an opinion on an MX-5 forums that a geometry setup isn't as effective if the bushes on the suspension are very worn.
I wondered if Tony has an opinion on this? Mk1 MX5s are now between 10 and 19 years old, so most will have either very old bushes, or will have been fitted with new, probably poly bushes. I wonder how many of the MX5s that Tony sees have had the bushes replaced?
On my car (a 1991 MX-5 turbo) the original bushes look like 17 year old bushes, the ARB bushes in particular look pretty tired. I might change some of the bushes at some point this year. I'm pretty sure changing the ARB bushes for e.g. polyurethane wouldn't affect the geometry setup, but I expect changing the bushes on the wishbones would.... Mind you, my wishbone bushes don't look half as bad as the ARB ones, so I'm not sure I'll bother with those just yet.