I have had the Gen 2 .25 Marauder since 2015 and other than playing with the settings of the hammer spring and throw with the TP at 5 open, I've done nothing to it and can find no reason to mess with a good thing. The only airgun I have that will out shoot the Marauder inside of 25 yards is my FWB 300s. And it better not be very windy for that to happen. My TX 200 in .22 cannot match the Marauder .25. For general shooting, I can count on 32 shots and up to 40 using mil dot hold over. JSB 25.43 at 840 fps. When shooting from a bench, I'll tether to my 68 ci bottle set at 2900 psi and shoot until I get tired of loading the ten magazines.
Unless you just like to tinker with mods, leave the gun alone internally. It doesn't need anything else. I did do the lawyer spring, but that is all. I have repaired, resealed and modified several of my 65 airguns over the years and yet I have had no reason to or desire to mess with the Marauder .25. It just doesn't need anything changed. Just my opinion.