SSDX 68 power mod is the only and most powerful modification for the X 68 also fixes the air chamber problem that still exist with both generations of the marker. You can also use this modification with CO2 using an on off adapter or a plug in the end of the modification you can get 150+ joules made in the USA completely.
https://youtube.com/shorts/wgslNQsTpFA?si=NhlrAxQQJ2Nm7Gmt