The Whisper is a wonderful, lightweight, powerful air rifle. Adding the Crosman Nitro Piston conversion delivers more benefits. You'll be ready to hunt small and medium-sized game and vermin with the Whisper + Crosman Nitro Piston. The non-removable noise dampener reduces the noise up to 52%, which means you won't spook game while hunting. Just because the Whisper is modestly priced doesn't mean you give up anything in the accuracy department! You'll be hitting your targets and making one-shot kills time after time. This just might be the ideal hunting gun! We measured the cocking effort with the metal spring, and it was 35 lbs. (Gamo lists it at 30 lbs.). The Crosman Nitro Piston cocks with 34 lbs. of effort. Here are the benefits of getting a Whisper with a Crosman Nitro Piston conversion: Smoother cocking Smoother shooting No spring torque No spring fatigue, even if you leave it cocked for hours Functions perfectly in cold weather Lasts longer than a metal spring Installed by our expert gunsmiths! NOTE: Installation of the Crosman Nitro Piston will delay shipment by 24 hours (or one business day) We tested the .22 caliber Whisper with both the metal & gas springs: Metal spring: 880 fps/PBA pellet; 739 fps/14-grain pellet Gas spring: 960 fps/PBA pellet; 740 fps/14-grain pellet Installation of the Crosman Nitro Piston has a 1-year warranty.