So, the guys at Daystar say they are 3" over stock. I'm not sure how accurate that is but it is in the ball park. I cut mine down with a hacksaw to make them the correct length. Next, at the top of the cup there is a bolt that holds it to the frame. That bolt is the same diameter as the one coming out of the top of the stop. Simply unscrew the cup and screw the new stop back in its place. Really that simple. You can use the old cup for stability but it isn't necessary. I did not use them in the front but I did in the back because the cup is what holds my rear spring lift in place. Using the cup with these stops means you have to shave a little rubber off but it isn't that big of a deal. I hope this helps.
Sorry for the delayed response, just installed them today! First off, don't be freaked about all the things those guys were saying about how bad these stops are. Another user sent me a private message saying that he has them and does some pretty hard wheeling without a problem. The consensus around here is that if you don't do exactly what the senior members do, you're an idiot.
I have the same bump stops and have no idea if they are correct or how to install them. Did a 2" lift and found out that my factory stops were crumbled. I still have the factory cups on but am puzzled about the new ones. I am curious what you found out from Daystar?