Egg
I used to have a Z boarded eggy for my Ion. My ion had all the bits and bobs on it, and was a fast lovely to use beasty. I was advised to upgrade my Z boarded eggy as it is probably holding my Ion back despite clearly being able to feed fast enough.
So I bought a pulse.... and to be honest I have to say I did notice a difference. A Z boarded Eggy is great, and still have it as a wet weather back-up as pulses don't really like getting damp.
If your on a budget stay with the eggy but try and get an eggy 3 or a z-boarded eggy 2, however if you can afford more go with a reloader B or a pulse. You will notice the difference, even if only slighlty.
EDIT: Oh, and eggs hold a LOT of paint when compared to the pulse or reloader.