I believe one item @marctronixx is referencing is possible bad brake fluid. Brake fluid is hydroscopic (collects water overtime) and can cause rusted internals and a soft peddle (due to boiling of fluid).these rotors have been discussed as not being worth the coin.
how long has it been since you changed your brake fluid? have you had your brake system checked overall? what type of fluid did you use if you did it yourself? i had 2 armadas and an infiniti qx and the factory /stock pads and rotors always performed as i expected.
Manufactures recommend bleeding fluid approximately every 2 years regardless of mileage. Doing so will often make a huge improvement in peddle feel and overall performance. Check this link for info: How to Bleed Brakes, Zeckhausen Racing
Another thing you should look into is bedding the brakes. This can often cure poor performance.
Check this link for the procedure: Bedding in Brakes, Zeckhausen Racing
I'm not a huge fan of Powerstop myself. I just went with Duralast gold (from autozone) for low dust but they perform well (though I am overdue for a brake bleed myself...).