I just recently installed the BDS YJ 3.5" springs on my CJ (along with a MORE SRS). I couln't be happier with the performance. My CJ is a daily driver, about 60 miles every day (just to work and back). It did look a little funny with 31's, but not too bad, now I have 33's and it is wonderful, handles great (after installing a YJ pitmsan arm), rides great, can't beat the warrenty! At least go big enough for 33's at first, you will want more soon. I am already planning a body lift.
Good Luck,
Shawn