The 510 Passthrough is 10000000x better. 2-3 Times more vapor than a Vapor King XL. No matter how hard I tried with 3 different fluids and different cartomizers, even with a passthrough, the vapor king wouldn't make enough vapor to satify my vapor needs. The 510 blows the vapor king away with anything I tried so far. Cart/Atomizer, Cartomizers and drip tip all make tons of vapor. Drip tip seems to make the most, but I think I might be able to get the cartomizer to make more if I dont overfill it. Only used it for 3 hours so far, but the 510 passthrough is KING!