I have one in my 98, previous owner did it. I've popped it out and drove without it and then put it back in a while ago just to see the difference. Biggest noticable difference is the shifts(firmer, a little quicker, and not so soon) and a little better throttle response. I dont know any real world numbers for it, however I do like it and would rather have it in while driving than stock. BUT, I would not have spent the big bucks on it in the first place if it were me. Unless you're getting a killer deal on it or building a jeep for just street speed, spend the money somewhere else where you'll notice more improvement.