My thoughts on this are summed up here
viewtopic.php?p=272243 (esp the comments from paladek on how the rear subframe is designed to float) and here
http://www.mr2oc.com/showthread.php?t=414661 and some of the comments from the OP here
http://www.supraforums.com/forum/showth ... on-thread.. regarding handling for the street.
Be sure and read the links in those threads as well. My feeling is that the best performance replacement for most of our rubber bushings would be higher durometer rubber like TRD used to produce (would love to see some of our vendors offer this). At the other end of the scale, Porsche did the same thing for the new GT3, maybe the best handling car in the world
http://www.elephantracing.com/tool-box/ ... erview.htm Note where they used higher durometer rubber rather than poly where the rear suspension arms mount to the chassis.
On our cars, since we don't have higher performance rubber mounts available, I'd use a combination. I think the most critical thing for road feel would be to use OEM front mounts with Kirk inserts rather than full poly and OEM rear subframe to body mounts. I think it's okay to use poly in other areas (except where OEM spherical bearings are called for) but I'd still use OEM where you can and where you can't go for the SuperPro bushes which seem to be a softer durometer than other offerings. I'd then tune your strut/spring combo and swaybars to get the relative amount of handling stiffness you prefer.