I have the KR808D-1 from V4L. I also have their premium/cool cartos. I have used their juice and many other company's juices.
Normal cartos from V4l and other companies produce limited vapor. When i started on the premium cartos, the vapor production increased by 75% IMO. I have never had any premium flavor carto or wow flavor carto not produce a large quantity of vapor.
My main juice/carto is V4L's Peppermint. it has an awesome taste, TH and vapor cloud. I use auto batts (regular size). I charge them once per day and go through 1-2 cartos per day. On a side note, the WoWboy flavor is a tobacco/chocolate/mint blend. very subtle and it is quite good. i personally add some spearmint to it from Rocky Mountain Vapor.....im more of a menthol/mint person
I have used V4L's premium menthol which also produces a large cloud. Same thing with the smilin' menthol juice in a blank premium carto.
I also buy juice from vermont vapor, liquidxpress and halo. Halo's juice produces an okay amount of vapor. Vermont and Liquid were almost as good as V4L wow juice with the vapor production and TH.
the process to find the right flavor and perfect vape situation to fit your needs is a complicated one, IMO. I found that VV cool mint is my go to menthol and V4L peppermint is my other go to mint flavor. i only use V4L's cartos since they are good $$, quick to ship, always good service and offer free-bees every time i have ordered.
All of this is IMO, but this has worked for me.
I hope this helps mate
-cheers