I got the Maximum Motorsports RLCA's for mine and can honestly say I didn't notice a lick of defference from stock. I'm sure they do something...just nothing measurable by feel, or at least that's how it was in my case.
it depends.. if you stockers are worn out and the bushings are womped then you will feel a difference in handling as well as possibly a little bit in the 60ft's at the strip. especially in a case like my 92 where the 105k stock arms and bushings were used with no quad shocks.. (bought it that way) I installed the X2C motorsports boxer St upper and lowers all for 139 with energy suspension bushing and it really tightened it up. http://www.corral.net/forums/showthread.php?threadid=351992