Hi Jared17.
You didn't say what resistance coils you have in the T3D or what wattage you are currently using for them, but let me give you some general information.
You will never get a lot of vaper from it compared to some of the newer clearomizers because of the constricted air flow. It's a good little tank for regular
vaping, but if you want a large volume of vapor, you will probably have to consider getting something else. You can increase the amount of vapor by increasing the power some, but you are still not going to see a large amount.
As for the best setting, there is no such thing. It all depends on where you prefer the flavor and vapor. Turn it up, turn it down, there is no one size fits all. I would start around 6 watts and increase from there - if you get a burnt taste, turn it down a notch or two.