Managed to achieve 415w+ TDP with the 3-resistor mod. Actually, 22Ohm or 47Ohm resistors are the best for this mod. 10Ohm is a little bit too small since nVidia changed their series resistor from 10Ohm to 20Ohm.
I also experimented with two conductive paints, carbon based, and silver based.
The carbon based paint has around 20-30Ohm resistance over a 1mm gap. The silver one only has about 0.1-0.2Ohms