The urethane will definitely last longer
if installed properly, with the proper amount of grease. They do firm up the suspension, as far as things deflecting in turns, which makes it feel like it handles better, and it does slightly. The thing is, urethane will not deteriorate like the rubber components do over time. And yes, urethane bushings can/will make noise if not installed according to the destructions that come with the bushings.
It all comes down to whether or not you wanna drive it and not worry about ever having to replace them again, or having the car Judged sometime down the road....
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Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"