As Nick mentioned earlier, you really could do with access to a chrono. Before and after readings are important as they'll tell you if you have improved things or not. Much more importantly you need to ensure you don't go over the limir. Supersports, especially in .22, can easily and comfortably exceed our 12ft.lbs limit. When I fitted a new standard spring (and TbT guides) to my 1986 .22 version, it was exceeding the limit by a wide margin yet felt very civilised to shoot. Two shortenings later it shoots at just below the limit with its most efficient pellet and feels very benign.
As also mentioned, you need that "stepped prong" to push down on the rear of the spring guide whilst clearing the pin. Beware that some of the pins in the trigger mechanism might be loose and fall out. And pay attention to trigger parts orientation as you'll most likely need to remove them to get the piston out. Looking at some images and schematics will help there.