I've installed an XS 24/7 front sight on my Romanian SAR-2, and it's not that bad - just unscrew/remove the front sight post on the rifle, and drive the front sight drum all the way out of the front sight assembly. If you have one of the C-clamp-looking AK sight adjustment tools, or the one made by B-Square, that makes it REALLY easy; otherwise, unscrew the front post with needle-nose pliers, and knock the front sight drum out with a hammer and punch(the punch is provided with your XS front sight).
BTW, it's best if you can secure the rifle in a bench vise, or at least C-clamp the rifle to a workbench; I managed to do everything without either a vise or a bench, but it took a lot more time and effort.
- Anyone else done this and have any advice? Thanks so much in advance!