Well I got the 3913 Hogue grips in, reshaped the insert it came with, shortened the 5906 grip pin, rounded the ends and touched them up with some cold blue. I then heated up a small metal pick and pushed it through from the inside of the grips, used a hand drill slowly from the outside stepping up bit sizes slowly. I got it dead center right off the bat so everything went smoothly.
They're on there tight and feel great in the hand. They're not perfectly straight, but it doesn't matter to me since it's now one step closer to being carried and it looks just like most BigDog grips I've seen on other CS9s.
There was no need to cut away anything for the side plate.
I also changed out the rear plastic sight with one from a 3913. Both are the same height, but I did have to remove some material to make it fit. The reason why I changed the rear sight is because it moved easily with a light tap from a plastic tipped jewelers hammer. It's plastic and has no set screw like the metal type so it was a must for me.
I shot it last Saturday as you see it in the pictures and all went very well. I need to take it out for another trip soon to see what defense ammo works best in it.