Springs and shocks

Can anyone tell me where to get a good rear shock and spring mod that will make the bike handle better?
And a good tyre manufacturer for an F2F.
The tyres are good but 7 years old…

Mine has a Wilbers 641 that is built for the VF. Apparently it is just an assembly issue and they build to suit.

But have heard that Hagon and Nitron also do decent options.