please do not waste your money on an expansion chamber. its just a empty chamber that is supposed to allow room for any liquid Co2 to expand into the gas form before it hits you internals. but it really doesn't do squat.

the palmer stabalizer is the way to go. it will regulate you Co2 and once broken in (2000 shots) it will hold the consistancy of your marker better then anything else you can do with Co2. (can't do this with an exchamber)

you will also be able to control the PSI level of you marker, you can lower it. Tippmann don't usually need all 800 psi of whatever to operate. I have lowered mine to 550 PSI an dmy A-5 still works fine. you can also raise it back up if needed. weather you lower the PSI or raise it back up, it will keep holding a consistant output flow into your A-5. you will see greater accuracy and less gas/air consumption with every day of play.

skip the X-Chamber, they are all hype.
Palmer Stabs are the real deal, actually, anything by palmer is the real deal and worth every penny.