A CO2 bottle will be filled to about 1800 PSI. Way more than a nitrous bottle is ever filled to. You have to have some sort of pressure regulator to get your PSI down around 80. I have a gauge on mine, but it is after the pressure regulator, so it only shows how much is going to the air cylinder. You can get a 2000 PSI gauge at a hydraulic store, but they are bulky and expensive. A typical air compressor will only pump up to 175 PSI. You can fill a bottle like this, but it will only last 2 or 3 shifts. If you are drag racing, no problem. If you are on the street, you won't get out of your neighborhood before its empty. A on board air compressor will keep it full, but it will run constantly. I didn't want that kind of drain on my battery.