Just so you don't think the Nissan was faulty...

BGTV8

Physics is the answer ............ not wanting to trivialise this BUT ........

Brakes convert kinetic energy of a moving vehicle into heat to slow it down.

The shorter the time that the heat builds up increases the max temp the pads see and greater the opportunity for heat to get past the pads and into the pistons which will transfer it to the fluid.

So, my suggestions are:
1. More cooling (lots more - maybe 2 x 3" ducts)
2. Put temperature paint on the rotors and calipers so you can see just how hot it is all getting
3. Consider titanium pad backing plates OR titanium shims
4. Check your data and compare to a buddies .... are you over slowing the car before rotating into a corner
5. Look to driving style - can you extend the braking zone with a trail-brake. If you carry the brake longer, you extend the time over which kinetic energy is dissipated equals less heat build up
6. Look to the rotors and rotor material .... the rotor is a heat sink so with greater mass comes greater ability to absorb temperature which means less temp into the pad/piston and ultimately fluid BUT the quid quo pro is a heavier hub/rotor/caliper assembly for the shocks to control in bump and rebound and more rotational inertia to affect performance - small but if you look at data, you should be able to see it
7. The other thing I forgot to mention is that pad material is also an effective insulator, so chuck your pads in the bin when there is 5mm or less pad material left on the backing plate - usually around 10mm overall including backing plate.

Your sig suggests DBA rotors and I reckon you've outgrown what is effectively a road car rotor so look to race rotors ..............

These guys do really good motorsport rotors BUT they are exie ...

http://www.brypar.com/product-catego...r-brake-discs/

This is a heat-management exercise and won;t be a cheap fix ....

Simplest and cheapest is to look to driver technique and that is about maximising mid-corner speed which reduces the speed you need to kill and the kinetic energy you need to turn into heat - and trail braking is one key technique.

Good luck !!