The difference in mods is all in the pins and switches, not the tube. The tube is mostly decoration. As long as the center pin in the 510 is made of a good conductive material and the switch makes solid contact with the neg end of the battery, the rest is just the resistance on your grounding. The difference in voltage drop between tubes made of different materials is less than .05V most of the time. If that means win or lose in a comp you have a problem with your build, not your mod. Most of the folks that win cloud comps win on lung capacity anyway. It doesn't matter how great your mod or your build is. If the next guy has bigger lungs, he's gonna win. When you start looking for gear, remember that density of the cloud makes a difference as well. If your atty is TOO airy, your cloud will be thin and won't win no matter how big it is.