The TFV4 is probably about as good as you can do for a prefab coil tank. You're power and resistance limited on that mod, though. It's supposed to not fire below .3 and it definitely won't go over 50 watts. Your best cloud on that mod will be found in the .4 ohm range. If you really want the best vapor and flavor on that mod, I'd suggest an RTA and learn how to build coils. Something like a dual 26/32 clapton build at .4 will be pretty cloudy in the 35-50 watt range. An Advken Ohmega or an Indulgence MT would get you there. For single coil, try a Lemo2. But if you want prefab, probably the TFV4. You'll be at the very bottom of the power range-- most of the coils are rated 40+ watts-- but that's all the power you have. Plus, the TFV has a dual coil RBA.