i recently got a Java 45/4500 nitro tank and i would like to know how good they are and how many shots you can get out of them. Also if there are any upgrades to make them shoot more shots plz tell me.
It's pretty much just like every other preset system out there, they don't vary too widely. Number of shots you'll get depends largely on your marker setup, as well.
You have a black dragun according to your signature, so I'm not exactly sure what sort of low pressure system you had in mind, but all a regulator does is help ensure that the air pressure going into your marker remains relatively constant.