Kanger T3s are simple and fairly reliable, but they're only ok for vapor production. The tight wicks simply don't bring
juice in quickly enough to have a lot of
juice available to vaporize.
That said, you can raise your wattage, which will raise your temperature. To up your wattage, you can send more voltage to the same atomizer (like you said) or put a lower resistance (less ohms) atomizer head on it like Lowlife said.
A lower resistance head with a smaller ohm number uses smaller wire in the atomizer. Since the wire is smaller, the same amount of voltage makes it hotter.
So, if you up your voltage or drop your resistance, you'll burn hotter. Great! What's the downside?
* If you vaporize fluid faster than it gets replaced by the wick, you'll get a dry, burn-y hit.
* The Kanger 1.8 ohm heads don't have a great reputation. They don't last very long, and some say they don't work as well.
* Some juices don't do well at high temperatures. Flavor production will often be worse.
My friends and I all started on Kanger T3s. Those of us who just want a simple, practical vape still use them. Those of us who want great performance (flavor, vapor) have moved on to carto tanks and RBAs.
My current lazy pocket-carry setup is a iClear 16 on a Vision Spinner battery. You need to keep it topped off, but it has the best vapor and flavor production of the clearomizers that I have tried.