I did the 2.5 RC lift and found, after install, that the brake lines were kinda tight, but I could still drive it. So, my next mod was extended brake lines. I also had a slight vibration, so, the next mod was a drop kit for the transfer case. (All the while, it is still drive-able, but I wouldn't want to take it wheelin').
I also notice that I will probably need to address my steering issue in the future. Next mod may be a drop pitman arm.
YJ Sean is right, each application varies, but the basic kit, allowing for 31" tires, will get you started. Just be aware, there may be more to do, maybe not. But that's the fun of it!
And don't forget the Jeep moto: Just Empty Every Pocket!
It's a Jeep Thing ... I do understand!
1993 Jeep Wrangler - 2.5" RC Suspension Lift, 31" Mud Tires, powered by 4 angry squirrels