with pure energy bottles you are probably better off changing the reg out rather that dissassembling it and fiddleing with the pressures using the shims unless you know a lot about them and feel very confident doing it
however i'm sure there is someone on here that would know how to do it and could possibly talk you through it or even better do it for you
you can buy a pure energy low pressure spring kit for around a tenner, its very simple to do, just make sure the bottle is empty and follow the instructions.