If your stock suspension you are replacing was new then it wouldn't give you that much more lift. Think about it, your stock suspension is sagging from years of use so you really don't get that much lift. And after it settles it will be less then what you have now.

 

I did use the RE 3.5" kit and i'm sure it was higher than most other 4.5" kits on the market. I was able to take it to Paragon one time before they closed. They were getting a large group together and then split them into different classes depending on modifications to the vehicle. I got stuck in the "slightly modified" group because I didn't have lockers. As the day went on I noticed people in front and behind me kept getting out of their vehicles to help spot me through an area, only to find out I was already through. The suspension worked really well. I ran 265/75/16 and I really liked the look of it.

The trick is with these XJs is that when you go higher you need to pay attention to suspension geometry. Usually around 4" in the front and the LCAs are angled so much that the ride becomes really harsh and rough. There's also a good chance you'll pick up vibrations from the rear driveshaft which could require a SYE as sometimes a TC drop doesn't cure the problem. If you're interested at all in ride quality either stay low with it or spend the coin on a long-arm kit and no spacers. Quality shocks help too.