Fellas, the guy's just after a bit of help. I started playing with a Spyder Aggressor. I started as a rec baller then moved up to tourny level. The spyder's damn accurate with a decent barrel, which will cost you about $60. I also stuck a four stage expansion chamber with low pressure chamber on it too and that helped to get the velocity a bit better. I don't know about Tippman's, so can't help you there. I've just sold me Aggressor, hjowever and upgraded to a JT Excellerator5.0. Bit of trouble with the velocity, but other than that, more accurate than the Spyder, the same price, and electro frame. Takes Spyder barrels (except Dye Excel!) and Inferno and Spyder spare's, including upgrading the venturi bolt to an Inferno one, which costs £22 in Britain, but wouldn't know about the States.
Hope that help's
PS I'm a hairdresser, so I don't know anything about physics threads or anyhting else, I just enjoy the way paint bursts on other tourny players.