Ok I have built several mods but funny enough I have never used a 2.5ohm atty. They have always been lr or hv attys. I have 6v mods, a newly built 5v mod, and a vv mod. So I picked up a 510 2.5ohm standard atty. I tried it on my 5v mod and it it gets very hot, I didnt like it at all. so I built a vv mod and I set it to 5v then 4.5, 4.3, 4.1, 4.0 and all seem to get hot. I know legnth of hit and breaks in between matter, and airflow through matter alot. It all seems like to much power for this atty and I cant figure it out. I have increased size on the air holes of the atty, and even filed the notches on the top of the fitting and little change. I also blew the atty out several times, seems ok. When I was assembling the box I tested the atty with the fitting in hand and got a few awesome hits, but now I am very disappointed. The case is rather big, and has plenty of airflow and when I sealed the fitting in place I only put a small bead of epoxy around the top, nothing near the bottom. (This was a test case I used and just ended up keeping my vv mod in it...not pretty but works) I can only guess the atty is my issue, I did test it and it is 2.5ohm. If they all were like this people definitely wouldnt be goung crazy over running them at 5v? Is there something else I could be doing wrong?