Well I went ahead and installed the huma reg, plenum, and heavy spring. Very glad I did. Stacking pellets at 60 yards and beyond. Maxed out at 960fps with 34gr, so I backed it down to 940. I still get 40 shots, a little more power, and its actually quieter. I adjusted the trigger a little more for my liking also. What a simple gun to work on as well.