They will change the pressure inside the bottle which can prove to be disasterous to your engine. Depending on which state you live in, if you live in a cold state, then a bottle warmer is a must. If you live in SoCal like me, a bottle warmer wouldn't be as important but if would also have to watch it if it heats up. Pretty much it comes down to you can't use nitrious when the bottles temp has went down or up significantly, thats where you will run into problems.