Beside aesthetics and poser appeal there really isn't much difference between most barrels. In my opinion the only thing worth bothering about is trying to find a barrel with a bore diameter that matches the paint you typically shoot. It won't make a night an day difference but matching your paint will slightly aid consistently and air efficiency. You could get more Shaft 3 barrel back kit (discontinued and hard to find) to give you more options with the front you already have or you could go with something like a Freak barrel kit which opens up a lot of options.