They are a pain in the arse to remove. Took me a couple of hours to do mine and Si's. The problem I found is they seaze on, and you can almost guarantee when you get the nuts to start turning, it will the make the ball socket come loose inside the plastic moulding.
I found using several sets of good maul grips, loads of penetration spray, and a shit load of elbow greese did the trick in the end.