No kits but i have used the sp teardrop, j&j ceramic, whisper, and various stock barrels
AIM Eagle body
Multiple bores, backs instead of inserts, mirror polish, easy one the eyes
This is a very nice system, it doesnt have as many bores as a freak or pipe system but its doesnt matter since you wont use many of those bores anyway. The inside of the barrels are polished to a mirror shine and shoot clean in 4/5 shots. Sometime the bakc is a little hard to get off the gun but that is to be expected. The tip has a rear o-ring so alignment is not a problem. There is a .685, .689, and a .693 back so all the major paint sizes are represented. For the money i dont think you could get a better barrel let alone kit.