-CMI Drop Forward
Adjustable rate of fire.
The Tippmann A-5 RT is a great upgrade. I got it separately on my A-5.
The trigger works in a way similar to the e-grip. Instead of firing a certain number of balls like the e-grip, you can control how many you shoot with the RT without having to configure it. All you have to do is gently pull the trigger (not a light though though, a slight pull) and it will fire as long as you hold the trigger down. With the Cyclone feed, you will never see a ball break or double feed.
Changing the sensitivity of the RT is easy. When you buy the RT, is comes with a small screwdriver (You could fit about 20 in your pocket). You don't even need the screwdriver, just use your fingernail so you don't have to bring that around.
Installation is kind of a pain in the ass. You have to take apart almost the entire gun. I am a newbie at that so I had someone else do it for me. If you know paintball guns, then you will have no problem with the installation.
I'd say buy the RT. You'd save $50 if you planned on buying the e-grip.
Depending on how much you shoot, you'll need to buy paint.