You're pretty much stuck with what you've got. You would have to increase the piston stroke length, or increase the diameter of the piston to get more swept volume, neither of which is practical. You can't install a power adjuster. Even a more powerful gas ram would just make it harder to cock, and probably ruin the accuracy. A good cleaning of the cylinder and piston, and some proper moly grease might get you a few more fps, (maybe 5 or 10) but nowhere near 45. I doubt that his breach seal is leaking. You don't mention which pellets he's using. Lighter pellets will give numbers closer to the 725, but manufacturer reported velocities ar almost always on the high side. Instead of trying to reach out to 50 yds., concentrate on stalking skills to get closer. Your accuracy will be better, the target will appear larger for better aiming, your terminal velocity will be higher, and you'll have less pellet drop.