You guys claiming "facts" about the Twist barrel may want to try them out or do some more reading before you spout such claims (which are often incorrect.)
1) The Tanio Koba Twist barrel does NOT twist the projectile. It does NOT work in the manner a real steel rifled bore barrel does by putting a twist on the bullet. What the TK Twist barrel does, is it twists the AIR around the BB to float it through the barrel and prevent it from touching the walls of the barrel (this is the theory and marketing claim.) By having it bounce in the barrel less, the trajectory is less affected, and as a result, shoots straighter.
2) The Tanio Koba Twist barrel does NOT make the hop up system useless - in fact, the hop up system is still very much required. In short barreled guns, I've had to turn the hop up to MAXIMUM to achieve the best results, otherwise, the range would be equivalent to use of the gun with a normal barrel. This shows that the hop up system is still working!
3) Use of longer versions of these barrels (such as in AEGs) shows that you can NOT simply put the hop up to maximum, and just like on standard hop up systems, you will need to play around to find that perfect spot to prevent flyers.