Has anybody upgraded their suspension bushings to urethane? If so does it improve the ride handling. Which brands are the best. What about better strut mounts?

 

A quick search of this forum will present you with hours of reading.
Yes people have changed them.
WJ

 

l have all poly bushes on front end along with my own poly top mounts.
Steers and handles like on rails.
My XKR has all the R options, including handling pack and 20" wheels and there was no noticeable loss of ride comfort. I cannot say if the same would apply with 18" wheel vehicles.
For the bushes, powerflex is the brand l went with.
My poly top mount also eliminates the common mount failure problem our cars suffer as a result of the foam components used. PM me if you wish to go this route.