Greg, do yourself a favor and get the 3M PPS system for your gun. No spilled paint on the car from a vent hole and you can hold the gun in any orientation to paint, as long as you keep it perpendicular to the panel.
http://www.youtube.com/watch?v=CIC2fuUAP4E
You don't have to get the dispensers, just a box of liners and the cups. The cups come two to a box. If they have the bonus pack box of liners it have a cup in it. You will also need the adapter, they run about $12 or so. You'll be happy you got it.