I installed one on my Citori XT Trap to add over an inch LOP, and am very happy with it. It works great, and allows for adjustments of LOP, up and down, and butt angle for fine tuning. Also great for changing seasons and heavy coats.
For installation, I used the Browning factory butt pad, and the screw holes lined up perfectly on that plate. For the wood side, the holes in the plate don't line up with the Browning holes. I didn't have a problem drilling new holes without filling the old. Some people plug the old holes before drilling new. (I actually called Graco to find out why the holes are different spacing, as it doesn`t make sense. They couldn`t really give me an answer, and wouldn`t ship me one with no holes drilled.

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You also need to bore a hole in the butt to allow the threaded tube to fit. I made a wood jig, pre-drilled with a hole-saw of the proper size, and attached it to the butt using the factory drilled butt pad holes, to act as a guide to use the hole-saw on the stock.
I can try to get some pictures if needed.
It takes some time to cut the aluminum plate down to size, and finish, but well worth it in my opinion. I have a second one waiting to go on another shotgun, when I figure out what I'm buying.