Changing the trigger is easy if you can screw out one screw then screw it back in. I have no idea what a s2 trigger looks like for mounting hole but my timney I just put in my s1 came with a different screw and elongated hole to fit a s2. So if the factory s2 trigger has a dedicated single hole it won't line up with the s1. May also be a different size screw and thread pitch I didn't look that close at the provided extra screw. I like the s2 trigger a lot compared to other factory rifles at that price point and wouldn't feel a need to replace one but I do like the timney more and may be a more viable option for you.. Just my .02