So I'm gonna start this topic for some of you who don't know what overboring & underboring is. There are alot of barrel kits out there that let you have the option of changing the barrel back to a smaller or larger bore size, like the evil pipe kit, red pepper stick, stiffi switch, deadly winds etc... and last but not least the freak kit. No the freak kit isn't the best it's just been around the longest. Why should you get one? I would say you don't need one but if you got the cash why not?Overboring-Where you choose a barrel bore size that is larger than what bore your paint is.Example- If your paintball bore size is a .689 (average) you would chose a barrel that is bigger like a .691 or .693.Why do people overbore?They believe that chosing a barrel that is bigger than the balls it is less restricting on the paint making it easier for that ball to exit the barrel. Underboring-Where you choose a barrel bore size that is smaller that what bore your paint is.Example-If your paintball bore size is a .689 (average) you would choose a barrel that is smaller like a .683 or .681Why do people underbore?They believe that it has a tighter controlled exit causing greater efficency and consistancy.Facts- -Overboring causes barrel breaks. How? When the ball exits the barrel because the ball is smaller than the barrel bore the paintball may not enter the barrel straight causing the ball the "hit" or rub against the barrel on one side of the barrel.-Overboring has reduced efficency. How? When the air pushes the ball forward some of it escapes around the ball. Meaning that not all of the air is used to propell the ball forwards, instead it is just being wasted.-Overboring has reduced consistancy. How? Because there is room for the air to escape around the ball not all the air is pushing the ball forwards so some shots more air might push the ball than another shot. Also the ball is "freely" flying out of the barrel meaning there is no control.-Underboring reduces barrel breaks. How? As weird as it sounds by underboring your pushing the ball thru a control. So the ball is "formed" to the size bore it is passing thru. By doing so the ball exits the barrel straight. When a sphere is compressed equally along it's circumference it is very very strong without breaking. Want an example? Go to your kitchen and take an egg, with your index and thumb on opposite sides of the egg squeeze. It broke because two forces were applied on two points of the egg, by doing so the egg flexed in either direction of the points you squeezed causeing it to brake. Now with your pointer finger and thumb wrap completely around the egg(like doorknob grip) and squeeze as hard as you can while applying equal amounts of force around the egg at the same time. By distributing the load or compression equally around the egg's circumference. Sure it's an egg and we're shooting paintballs but the concept still applys.-Underboring has improved consitancy. How? By compressing the paint into a smaller hole than the paint there is no or little room for the air to escape around the ball meaning the majority of the air is used to propell the paintball. Meaning you'll have better air-paint efficency. AND you'll also see improved consistancy over the chronograph in terms of Feet Per Second. Why? By compressing the ball you're sending the ball thru a control. Meaning it will take nearly the same amout of air to move a ball thru the barrel back nearly everytime, in the same effect the ball will have the same amount of "drag" while passing thru the barrel back.Conclusion-Is one better than the other? I have presented the facts to you and you can make a decision for yourself. If what you have/are doing now has been working for you and you don't wanna change then more power to you!Hope this helps understand the topic, I have given you my understanding of each. I'll probably edit this later for any mistakes i made. It's late and I like to talk or type when im tired so i figured I'd do something productive instead of being on facebook chat or something stupid lol.