may not have to cut the bumper at all, every car is different.
the work you will have to do is inside the fender well. will need to remove the bump stops and stuff like that. might have to use a BFH and massage inside there, too, hard to say. every car is different, just have to play with it.
I had to take out the bump stops, I'm running the 12.5's in the rear, had to bang the inside a litttle, they don't rub at all unless I really dive into a turn, but I don't do that at all w/the skinnies I drive on everyday