Let's talk about leaks now. Care should be taken to be sure the fittings used are fairly new and even at that, you should perform a simple leak check of your system by spraying it down with Windex or the equivalent. If you've got a leak, this will show it. While you're spraying, spray down around the valve area of the bottle, as sometimes the o-rings on the valve do go bad. Air shifter cylinders and solenoids usually tend to be pretty leak proof, however, that's not the case with throttle stop components.
Most throttle stop cylinders on the market today have rubber cup rings on the actuating piston.
CO2 is a relatively cold, dry gas, which means that it can tend to dry out any lubrication that may be on the sealing rings. A little dirt or dust entering the system, and you've got an annoying leak. I tend to tell my customers that every so often, a squirt of a little WD-40 or the equivalent into the air inlet side of the cylinder will go a long way toward alleviating leaks and allowing the piston to glide effortlessly in and out. One thing you need to remember is that, leaks are a part of the game. Most racers know that after a day's racing, it's wise to reach over and shutoff the CO2 bottle valve.