I have it on my 2001. It has a lot of flex and always keeps its wheels on the ground. I had noticed that on the street the rear end leans over more than a leaf sprung and I had been thinking of fitting a Currie anti-rock in the rear but I may go for firmer rear springs first.
A picture of it was posted on

recently that another member commented on saying the rear end looked too soft. Looking at more photos and some video, I agree. I have been testing how it behaves in certain situations but I'm not so certain now if it needs more roll stiffness (swaybar) or firmer springs.
I haven't had the chance to talk to Clayton or Adam yet to see what they suggest. Having it loaded with gear and a 35" tire on my bumper mounted carrier makes a noticeable difference to handling compared to being empty.
There is not much room to route the exhaust system to the rear but it can be done if you need to stay legal. I have had to reposition my rear axle shock mounts further inboard to make sure the shock body doesn't get crushed at full stuff on the exhaust side. I have some slightly shorter Bilsteins waiting to go on soon.
Most people have an exhaust turn down just after the transfer case. It wasn't an option for me legally. The downside is that my floor gets very hot and the carpet backing behind the front seat is melting. I'm going to experiment with some painted exhaust wrap from behind the cat to the rear axle. Hopefully this will prevent the rear foot well from getting too hot.
Overall, I am pleased that I went for Clayton's kit. If I was going to build another XJ I would go for the same again.