I pulled the shifter base bushings out of the Eclipse and popped them into the Evo today. For anyone thinking this is going to make a huge difference, I submit to you that the entire shifter base is made out of plastic. I wasn't expecting a significant change of behavior, and I got exactly what I expected: a mild improvement in transmission activity transferring to my hand, but that's about it. The Laser and Eclipse both improved dramatically after changing those out, which probably says more about the state of the original bushings in those two cars than the stiffening qualities of the metal bushings.
So, if you're thinking of adding these, do yourself a favor: get a cheap set off of eBay; they're not worth much more than the cost of the metal and the time turning them in a lathe, but they're probably the only thing you can do to stiffen up the shifter.
Man, I'm spoiled by the WRX shifter, after we installed a set of poly bushings on that one...