You are using the KR808 from V4L? I just got an 808 (different vendor) with V4L cartomizers. I also have a harshness problem. I posted something about it in another post and was told that the 808 is a true 3.7 volt device as opposed to teh 510 which is about 3.2 volts. I have a 510 and have never had a harshness problem. It is a smooth draw and no throat burning. I use straight PG juice. I guess the voltage is too high for us? I also used to smoke Marlboro lights. The 510 got me off regular cigarettes. I am happy with it but decided to try the 808 because the battery life is supposed to be twice as long as the 510. Unfortunately, I don't think I am going to be using it much because my throat feels like I've been drinking bleach. 