i'm not such a fan of the empire kit. i think the bore sizes are too big... but it really depends on what paint you use. i have a bizerk kit with .685, .687 and .689 and those sizes are perfect.. except for zap sport, that stuff was too big, but it's bad paint anyway
edit: if it's worth mentioning partly why i got the smaller sizes is also cause i was annoyed at balls rollin outta my pump.. and the balls at the fields in my area seem particularly small so you should consider the size of the balls you're goin to be usin mostly.