well, from seeing the reviews, seems like the v2.5 came with long wicks , the newer V2.5/3 are the ones with the short wicks. If you get the ones with the longer wicks I hear its easy to trim the wicks to your liking. some say the shorter wicks dont mute the flavor, which I guess makes some since the juice doesnt have to travel as long and sort of filter thru the wicks. Some even leave one of the wicks long and trim the others. I guess the longer wicks gives the user a choice. I have made some changes to mine which has really enchanced my vape. I made the vents along the threads larger, just a tad. I also cut the little plastic cap on top of the atty just a tiny bit and sanded down the center pin on bottom just enough so it still sits higher than the threading, lets it sit in better but it still tends to push the center pin on my KGO battery. No problem though I just lift the center pin with a jewelers screwdriver . Just be careful, there are some how to on modding your VIVi because every time you try little changes to take the chance of messing them up.