Today I finally put on my RCE 25.5mm hollow rear sway and Kartboy endlinks, and the difference is very noticable. My car feels much more solid and predictable through turns. I'm not sure how much is due to the sway and how much the endlinks, since I put them on at the same time, but I'm quite pleased with the overall suspension upgrade.
If anyone out there would like my OEM endlinks and/or bushings as spares, I'm happy to give them away. Just pay me for shipping (although I won't turn down donations if you feel like including an extra few bucks). PM me if interested.