Here are UC kits from my experience: Every kit has its own personality or way it likes to be pumped for maximum smoothness. Some are easier than others to do so.
CCI/Wevo Kit (contact Mike @ CCI) - Good solid kit, smallest, but not the smoothest. By design there is some inevitable side-to-side play. Have to "pump it the right way" for it to be smooth. Pump it the wrong way (for example with some twisting action) and it will get stuck.
Original style Rainman UC kit - Good solid kit, larger and smoother than the CCI/wevo kit. By design, eliminates side-to-side play but has some vertical up/down play. This UC kit is easier to "pump it the right way." Harder to pump it wrong. Returns smoother than the CCI/wevo kit.
Original Rainman UC kit with CCM Tgrip - Same as above. No play in any direction. Even easier to "pump it the right way." This is my favorite thus far.
Here are UC kits I have not tried:
Desert T1 UC kit - Replaces the Vertical ASA, makes the VASA larger. Looks solid.
New Style Rainman UC kit - Looks more solid than old style kit. Repositions the Vertical ASA, alters the look of your marker. Able to use stock thumbscrew (easy to take apart your marker)
Last edited by m1yeh; 02-14-2013 at 12:20 PM.