The Twins have multiple options - stiffer bushings, solid aluminum bushings, Perrin lockdowns and Cusco rack brace. I went with the cheapest stiffer bushings I could find (at under $20 shipped) as the other options are quite a bit more expensive.
This thread was the main reason I saw no point in splurging for the more expensive solutions. Plus the Cusco rack brace doesn't look like it can do something useful (although there are some positive reviews around here for that).