I have the MSR version. First off, I do not recommend this kit with a 1.4 or higher spring. I know it's advertised that it can handle it but with a 45 degree trigger, it will just grind and slam fire. Most I would do with this as is, is a 1.2 spring. If you want to go to a higher spring, you will need a 90 degree trigger system and bolt. Other than that, it will improve FPS and adds a more sturdy feel to the bolt.